SALMONIDAE. The distinguishing features of this family of fishes are described in technical language in the article ICHTHYOLOGY (vol. xii. p. 693), and it is un-necessary to repeat the definition. The most conspicuous of the external characteristics is the presence of two dorsal fins, of which the anterior is well developed and supported by the usual jointed bones known as fin-rays, while the posterior is thick and fleshy, rounded in outline, and desti-tute of rays. The posterior fin is thus a rudimentary organ, and it is commonly called the adipose fin. There are two other families of fishes which resemble the Salmonidx in the arrangement of the dorsal fins—the Percopsidae and Ilaplochitonidae; but the former consists of only one species, found in the United States, and the latter is confined to the southern hemisphere. Amongst British fishes a Salmonoid can be always recognized by its dorsal fins.

The Salmonidx retain the open communication of the air-bladder with the intestine, and the original posterior position of the pelvic fins,—features which characterize the division of Teleostei known as Physostomi. In the great assemblage of bony fishes known as Physociisti, these features are lost in the adult condition. It is known that in all cases the air-bladder develops in the young fish as an outgrowth or diverticulum from the intestine; and it is obvious from a survey of Vertebrates in general that the posterior limbs belong originally to the neighbourhood of the anus. It follows therefore that in these features the Salmonidx, and all the Physostomi, are more similar to the early ancestors of the bony fishes than are those species in which the air-bladder is closed and the pelvic fins have an anterior position.

In the Salmonidae the characteristic Teleostean pseudo-branchia is present. This organ is the diminished remnant of the series of gill-lamellae belonging to the posterior face of the hyoid arch, as the pseudobranchia in Elasmobranchs is the rudiment of the series of gill-lamellae belonging to the posterior face of the mandibular arch. The bones known as maxillae form portion of the boundary of the upper jaw in Salmonidx; in many fishes they are excluded from the jaw margin by the backward prolongation of the premaxillae. There are no scales on the head in this family, and there are no fleshy filaments or " barbels " in the neighbourhood of the mouth as there are in many bony fishes—for example, the Cod, in which a single short barbel is attached beneath the lower jaw. The pyloric append-ages, cascal diverticula of the intestinal tube immediately behind the stomach, are nearly always present in consider-able numbers. In the female Salmon the oviduct, the tube connecting the ovary with the exterior, is wanting; the eggs when ripe escape from the surface of the ovary into the abdominal cavity and pass thence to the exterior through a pair of apertures in the body wall situated one on each side of the anus; these apertures are the abdominal pores. In the male salmon there is a duct to the testis, and the semen is extruded through it in the usual way. Fertilization takes place outside the body, the spermatozoa and eggs uniting in the water. '

Distribution.—Salmonidx are found both in the sea and in fresh water. Most of the marine species inhabit the deeper parts of the ocean. Many of the freshwater forms pass a portion of their lives in the littoral parts of the sea, ascending rivers when adult every year in order to deposit their spawn; that is to say, many species are anadromous. Some are confined entirely to fresh water. The Salmonidx are, with the exception of one species indigenous to New Zealand, peculiar to the temperate and arctic regions of the northern hemisphere. Fossils belonging to the family are found in strata of Mesozoic age. Osmerus occurs in the greensand of Ibbenbüren, and the schists of Glarus and Licata. Mallotus villosus, indistinguishable from the living Capelin, occurs abundantly in clay in Greenland, the geological age of the bed being unknown. Osmeroides acrognaihus and Aulolepis are fossil genera occurring in the chalk near Lewes in Sussex, and were probably deep-sea Salmonoids. The introduction of certain species into new areas by human agency, which has been effected recently, and is still going on, will be described in another section.

:—
1. Salmo, Artedi (Salmon and Trout). Scales small. Cleft of mouth wide; maxilla extending backward to below or behind the eye. Dentition well developed ; conical teeth on the jaw bones, on the vomer and palatines, and on the tongue; none on the pterygoid bones. Anal fin short, with fourteen or fewer rays. Pyloric appendages numerous. Ova large. Dark transverse bands, known as "parr marks," present on the sides of the body in the young stages of life.

2. Osmerus, Cuv. (Smelts). Scales of moderate size. Cleft of the mouth wide; maxilla long, extending to or nearly to the hind margin of the orbit. Dentition well developed; teeth on the maxilla and premaxilla smaller than those on the mandible; transverse series of teeth on the vomer, several of which are large and fang-like ; a series of conical teeth along the palatine and pterygoid bones ; strong fang-like teeth on the front of the tongue, several longitudinal series of smaller ones on its posterior part. Pyloric appendages short and few in number. Ova small.

3. Coregonus. Scales of moderate size. Cleft of mouth small; maxilla rather short, not extending back beyond the orbit. Teeth minute, or absent altogether. Anterior dorsal fin with few rays. Pyloric appendages numerous. Ova small.

4. ThymaUus, Cuv. (Graylings). Similar to Coregonus, but having a long anterior dorsal with many rays. Small teeth on jaws, vomer, and palatine bones.

5. Argentina, Cuv. Scales rather large. Cleft of mouth small; maxilla not extending to below the orbit. Teeth wanting on jaws; minute teeth on the head of the vomer and fore part of the palatines; series of small curved teeth on each side of the tongue. Dorsal fin short, in advance of the pelvic. Pyloric appendages few or in moderate numbers. Ova small. The most conspicuous peculiarity of this genus is the flattening of the sides to plane surfaces bordered by keeled ridges, so that the transverse section of the fish is hexagonal.
The following eleven genera include no British species :—

6. Oncorhynchus, Suckley (Ann. Lye. Nat. Hist., 1861). Simi-lar to Salmo, except that the anal fin has more than fourteen rays.

7. Braehymystax, Günther. Intermediate between Salmo and Coregonus.

8. Luciotrutta, Günther. Migratory trout from North America.

9. Plecoglossus, Schlegel. Body covered with very small scales. Cleft of mouth wide ; maxilla long. Dentition feeble ; premaxilla with few small conical teeth. Ends of mandibles separate at the chin, the mucous membrane between them forming folds and pouches. Tongue very small, with minute teeth.

10. Eetropinna, Gill. Similar to Osmerus.

11 and 12. Hypomesus, Gill, and Thaleichthys, Girard, are allied genera.

3 This is the generic distinction adopted by Dr Günther. Suckley's original diagnosis was the prolongation of both jaws in the males.'

13. Mallotus, Cuv. (Capelin). Scales minute, somewhat larger along the lateral line and along each side of the belly. In mature males those scales become elongate, lanceolate with projecting points. Cleft of mouth wide ; maxilla very thin, lamelliform, extending to below middle of eye. Dentition very feeble ; teeth in single series. Pyloric appendages very short, few. Ova small.

14. Salanx, Cuv. 15ody elongate, compressed, naked, or with small, exceedingly fine deciduous scales. Head elongate and much depressed, terminating in a long, flat, pointed snout. Cleft of mouth wide. Jaws and palatine bones with conical teeth, some of those on premaxilla and mandibles being enlarged ; no teeth on vomer ; tongue with single series of curved teeth. Anterior dorsal fin far behind ventral, in front of anal; adipose small. Pseudo-branchiae well developed; air-bladder none. Alimentary canal quite straight; pyloric appendages none. Ova small.

15. Microstoma, Cuv. Body elongate, cylindrical, covered with large thin silvery scales. Cleft of mouth very small; premaxilla very small; maxillse very short and broad. Eye very large. Narrow series of very small teeth in the lower jaw and across the head of the vomer ; no other teeth. Dorsal fin short, inserted behind the ventrals, but before the anal; adipose fin present in most young specimens, frequently absent in old ones. Pseudo-branchise well developed; air-bladder large. Pyloric appendages absent ; mucous membrane of stomach with numerous large papilla?. The genus is allied to Argentina.

16. Bathylagus, a genus of deep sea Salmonoids discovered by the " Challenger " in the Atlantic and Antarctic Oceans at depths of 1950 and 2040 fathoms.

Species.

1. Genus Salmo. The difficulty of defining and distinguishing the species of this genus is considerable, and much diversity of opinion on the subject exists among ichthyologists. Many of the species are extremely variable, so that some individuals of one resemble the more aberrant individuals of another; the species are seldom separated by conspicuous differences. The individuals of a given species vary considerably with age and sex, and also with habitat and external conditions. Many of the species are capable of breeding together and producing fertile offspring. The characters which are most constant, and on whose differences the distinction of species chiefly rests, are as follows :—(1) the form of the preeoperculum (the horizontal breadth of this bone at its lower portion is always small in the young, but in the adult it is greater in some species than in others; (2) width and strength of maxillary in adult); (3) size of teeth; (4) arrangement and per-manence of vomerine teeth ; (5) form of caudal fin; (6) pectoral fins ; (7) size of scales; (8) number of vertebra? ; (9) number of pyloric appendages.

In all the species of Salmo there are teeth in the vomer. In the Salmons proper and in the Trouts there are, in the young, teeth both on the head and body of that bone, but in some species on the body only; some of the teeth on the body are deciduous, and are in most of the species shed at an early age. In the Charrs there are teeth on the head of the vomer but none on the body of the bone at any period of life, and none of the vomerine teeth are deciduous. The species of true Trout are confined to fresh water, and are not migratory. In accordance with those peculiarities some zoologists have divided the genus Salmo into three subgenera,—Salmo sensu restricto, Fario, and Salvelinus. But modern authorities retain only two subdivisions, —the subgenera Salmo, including migratory Salmon and non-migratory Trout, and Salvelinus, the Charrs.

A. Subgenus SALMO.—A vast number of species of Salmo have been described ; in the Brit. Mus. Cat. Dr Giinther distinguishes fifty-two, of which seven are confined to the British Islands and four are found both in the British Islands and other parts of the world. Mr Day on the other hand considers that all the indi-genous Salmon and Trout of the British Islands belong to two species, Salmo salar and Salmo trutta,—Salmo levenensis and Salmo fario being varieties of the latter ; the rest of the described British species he considers as local varieties or subvarieties of

(1) Salmo salar, L. (the Salmon). B. 11-12 ; D. 14 ; A. 11 ; P. 14; V. 9; L. lat. 120; L. transverse HzlS- Vert. 59-60: Csee. pyl. 53-77. Attains to a length of 4 to 5 feet; female mature at a length of about 15 inches. PrEeoperculum with a distinct lower limb and with the angle rounded. Head of vomer subpentagonal, as long as broad, toothless ; the body of the bone with single series of small teeth which are gradually lost from behind forwards so that older examples only have from one to four left. Hind part of body elongate and covered with relatively large scales. Young with about eleven dusky transverse bars on the sides ; half-grown and old specimens silvery, with small black spots in small number ; spawning males with numerous large black and red spots, some of the red spots confluent into more or less extensive patches, especi-ally on the belly. An anadromous species, inhabiting temperate Europe southwards to 43° N. lat.; not found in Mediterranean ; in Asia and America southwards to 41* N. lat.

1 In the formula usually preceding the diagnosis or description of a species of fish, B —number of branchiostegal rays; D —number of rays in dorsal tin ; P = ditto in pectoral fin; A = ditto in anal fin; V=ditto in ventral fin; L. lat. = number of scales along the lateral line ; L. transverse=number of scales in the oblique transverse row of the widest part of the body, the numbers above and below the line in the fraction being those of the scales above and below the lateral line respectively.

No varieties of Salmo salar are recognized in Europe, but in North America there occurs one Salmonoid which is considered by different authorities either as a variety or a sub-species, viz., Salmo salar, var. sebago, L. lat. 115. Body and dorsal and caudal fins with subquadrangular or subcircular black spots. Is non-migra-tory and occurs in some of the lakes of Maine and New York in the United States ; these lakes have no communication with the sea. This form is called variously the Landlocked Salmon or the Schoodic Salmon.

The true Salmo salar on the American shore of the Atlantic is sometimes called the Penobscot Salmon.

(2) Salmo trutta, Fleming; Salmo criox, Parnell (Fishes of Firth of Forth) (Sea-Trout, Salmon-Trout, Bull-Trout). B. 11 ; D. 13 ; A. 11 ; P. 15 ; V. 9 ; L. lat. 120 ; L. transverse §|ff|; Vert. 59-60; Csec. pyl. 49-61. Attains to a length of about 3 feet; female mature at a length of 10 to 12 inches. Head of vomer triangular, as broad as long, toothless, body of the bone with a longitudinal ridge armed with a single series of teeth, which are deciduous ; generally only the two or three anterior ones found in examples of more than 20 inches in length. Silvery, sometimes immaculate, usually with more or less numerous X-shaped spots; spots on the head and dorsal fin round and readily disappearing. Young (parr) with nine or ten dusky cross bars ; grilse with top of dorsal and pectoral and with hind margin of caudal black. A migratory species, occurring in the rivers falling into the Baltic and German Ocean; numerous in Scotland, less frequent in English and Irish rivers.

(3) Salmo cambricus, Donov. (Brit. Fishes) (the Sewen of Couch, Salmon Peal). B. 10-11; D. 14; A. 11-12; P. 16; V. 9; L. lat. 120-125; L. transverse ; Vert. 59; Csec. pyl. 39-47. Attain-ing to a length of 3 feet; female mature at a length of from 12 to 13 inches. Praoperculum with a distinct lower limb, with the angle rounded and with the hind margin convex or undulated, subvertical. Head of vomer triangular, broader than long, toothless in adult examples, armed with a few teeth across its hinder margin in young ones ; body of the bone with a sharp longitudinal ridge, in the sides of which the teeth are inserted, forming a single series, and alternately pointing to right and left. In pure-bred specimens these teeth are lost in the grilse state, so that only the two or three anterior remain in specimens more than 12 or 13 inches long. Fins of moderate length ; caudal fin forked in parr stage, slightly emarginate in grilse, truncate in mature specimens. This species loses the parr marks very early, when only 5 to 6 inches long ; it is then bright silvery. Greenish on the back, with few small round black spots on the head and sides. This coloration remains nearly unaltered during the further growth of the fish, but the spots become more irregular, indistinctly X-shaped. An anadromous species, occurring in rivers of Norway, Denmark, Wales, and Ireland. Mr Day (Fishes of Great Britain) considers this form as merely a variety of Salmo trutta.





(4) Salmo fario, L. (Trout). Dr Giinther distinguishes two varieties ;—

(a) Salmo fario gaimardi; Salmo gaimardi, Cuv. and v'al.; Salmo trutta, Gaiinard (Voy. 1st. and Groenl., Atl. Poiss., pi. 15, fig. A). D. 13-14 ; A. 11-12 ; P. 14 ; V. 9 ; L. lat. 120 ; L. trans-verse ||-; Csec. pyl. 33-46; Vert. 59-60. Largest specimen observed, 15 inches; female mature at a length of 7 or 8 inches. Head of vomer triangular, small, broader than long ; vomerine teeth in a double series sometimes disposed in a zigzag line, persistent throughout life. Sides with numerous round or X-shaped black spots ; upper surface and sides of the head and the dorsal, adipose, and caudal fins usually with crowded round black spots ; dorsal, anal, and ventral with a black and white outer edge. Found in Iceland, North Britain, Ireland, Scandinavia.

(b) Salmo fario ausonii ; Salmo ausonii, Cuv. and Val. (the common River-Trout). Formula as in a, but Vert. 57-58. Attains to a length of 30 inches ; female mature at a length of 8 inches. A non-migratory species, inhabiting numerous fresh waters of Central Europe, Sweden, and England, and rivers of the Maritime Alps.

The following forms are peculiar to the British Islands :—

(5) Salmo levenensis, Walker (Worn. Mem., i. p. 541) (Loch Leven Trout). D. 13 ; A. 11; P. 14; V. 9; L. lat. 118 ; L. trans-verse §-$; Csec. pyl. 68-80; Vert. 59. Maximum length 21 inches. Teeth moderately strong ; the head of the vomer triangular with a transverse series of two or three teeth across its base ; the teeth of the body of the vomer form a single series and are persistent throughout life. Upper parts brownish or greenish olive; sides of the head with round black spots ; sides of the body with X-shaped, sometimes rounded, brown spots. Dorsal and adipose fins with numerous small brown spots. A non-migratory species, inhabiting Loch Leven and other lakes of southern Scotland and northern England. This species is considered by Mr Day as a variety of S. trutta.

(6) S. brachypoma, Giinther ; S. eriox, Parnell (Fish. Firth of Forth). D. 13 ; A. 10-11; P. 14 ; V. 9; L. lat. 118-128 ; L. trans-verse f-J ; Csec. pyl. 45-47 ; Vert. 59. Prceoperculum with scarcely a trace of lower limb. Teeth rather strong; those of the vomer in double series, but in zigzag line'. Most of them are lost in specimens 17 inches long, only a few of the anterior remaining. Sides of the body with X-shaped or ocellated black spots, some red spots along and below the lateral line ; dorsal fin with round black spots. Dorsal, anal, and ventral fins with a white and black outer margin in young examples. A migratory species, from the rivers Forth, Tweed, and Ouse. According to Mr Day, it is identical with the White Salmon of Pennant and Salmo albns of Cuv. and Val., all of them being considered by Day as a variety, S. albus, of Salmo trutta.

(7) S. gallivensis, Giinther. An anadromous species from Galvvay, distinguished by the acutely pointed but not elongate snout, broad convex head, small eye, feeble teeth, feeble maxillary and mandible, and by extremely thin and short pyloric appendages, which are not longer than one inch nor thicker than a pigeon's quill. According to Day a variety of <S. fario.
(8) S.ferox, Jard. and Selby (Edinb. New Philos. Journal, 1835, xviii.). A non-migratory species inhabiting the large lochs of the north of Scotland and several lakes of the north of England, Wales, and Ireland. Prasoperculum crescent-shaped, the hinder and lower margins passing into each other without forming an angle. According to Day a variety of S. fario.

(9) S. orcadensis, Giinther, from Loch Stennis in Orkney.

(10) S. stomachicus, Giinther (the Gillaroo). From lakes of Ireland. Thick stomach. Feeds on shells (Limneeus, Ancylus).

(11) S. nigripinnis, Giinther. Non-migratory species inhabiting mountain pools of Wales, also Lough Melvin, Ireland.

Day mentions also the following varieties of S. fario:—

S. cornubiensis, Walb., Artedi; Swaledale trout, from Swaledalc, Yorkshire ; and Crassapuill trout, from Loch Crassapuill, Sutherlandshire.

Many species of Salmo exist which are confined to limited areas in the continent of Europe. An account of these is given in the Brit. Mus. Catalogue, which also contains references to the litera-ture. One of these, 8. macrostigma, Dumeril, is a non-migratory form occurring in Algeria, and is the southernmost species of the Old World. Three non-migratory species exist in the rivers belonging to the basin of the Adriatic. In the Alpine lakes of central Europe five species are known, which resemble in habits the forms found in British lakes, ascending the streams which feed the lakes, in order to spawn. Two of these species inhabit the Lake of Constance, one the Lake of Geneva. Fario argenteus, Cuv. and Val., found in the Atlantic rivers of France, is con-sidered by Dr Giinther a distinct species, by Mr Day as a synonym of S. tridta. One migratory species is known from the Eidfjord river in Norway ; two land-locked species from Lake Wener in Sweden.

The species of Salmo belonging to the Pacific Coast of North America have been described by Richards in Faun. Bor. Amer., by Suckley in Nat. Hist. Washington Territory, and by Girard in Proc. Aeacl. Nat. Sc. Philad. Only one species need be mentioned here, and that on account of the importance it has acquired in connexion with the work of the United States Fish Commission :—

Salmo irideus, Gibbons (Proc. Cat. Ac. Nat. Sc., 1855, p. 36); Salar iridea, Girard (Proc. Acad. Nat. Sc. Philad., 1856, p. 220 and U. S. ___. _. E. Explor.—Fish, p. 321, pi. 73, f. 5, and pi. 74) (the Californian, Mountain, or Rainbow Trout). B. 10 ; D. 14 ; A. 14 ; L. lat. 140. Caudal deeply emarginate. Body and dorsal and caudal fins with numerous small black spots. A non-migratory species in rivers of Upper California.

For the same reason as in the preceding case, the following species of the eastern slope of the North American continent is introduced:—

Salmo namaycush, Penn (Arct. Zool., ii. p. 139), Cuv. and Val. (xxi. p. 348) (Lake Trout). B. 11-12 ; D. 13-14 ; A. 12 ; V. 9 ; L. lat. 220. Prseoperculum very short, without lower limb ; head very large. Teeth strong ; those on the vomer persistent through-out life, and in single series. Inhabits all the great lakes of the northern part of North America.

B. Subgenus SALVELINUS :—

Salmo alpinus, L. (the Charr, Yarrell, Brit. Fishes, 3d ed.). D. 13 ; A. 12 ; P. 13 ; V. 10 ; L. lat. 195-200 ; Vert. 59-62 ; ____. pyl. 36-42. Body slightly compressed and elongate. Length of head equal to height of body in mature specimens and two-ninths or one-fifth of total length ; maxillary extends but little beyond the orbit in the fully adult fish. Eye one-half, or less than one-half, of the width of the interorbital space. Teeth of moderate size. Inhabits lakes of Scandinavia, Scotland (Helier Lake, Hoy Island, Orkneys; Sutherlandshire ; Loch Roy, Inver-ness-shire), and probably Iceland.

S. killinensis, Giinther (Proc. Zool. Soc, 1865, p. 699). D. 14-15 ; A. 13 ; P. 13 ; V. 9; L. lat. 180 ; Vert. 62 ; ___. pyl. 44-52. Head, upper parts, and fins brownish black; lower parts with an orange-coloured tinge in the male; sides with very small, light, inconspicuous spots. Anterior margins of the lower fins white or light-orange-coloured. Loch Killin, Inverness-shire. Considered by Mr Day as a variety of S. alpinus.

S. willughbii, Giinther (Proc. Zool. Soc, 1862, p. 46, pi. 5); Charr, Wiliughby (Hist. Pise, p. 196), Penn (Brit. Zool), and Yarrell (Brit. Fish., 3d ed.) (the Charr of Windermere). D. 12-13 ; A. 12 ; P. 13-14 ; V. 9-10 ; L. lat. 165 ; Vert. 59-62 ; ____, pyl. 32-44. Sides with red dots ; belly red ; pectoral, ventral, and anal with white margins. Lake of Windermere ; Loch Bruiach (Scotland). Considered by Mr Day as a variety of S. alpinus.

S. perisii, Giinther (Ann. and Mag. Nat. Hist., 1865, p. 75); Torgoch, Wiliughby (Hist. Pise.) and Penn (Brit. Zool.) (the Torgoch or Red Charr). D. 13 : A. 12 ; P. 12 ; V. 9 ; L. lat. 170 ; Vert. 61 ; Ca3c. pyl. 36. Sides with numerous red dots ; belly red in the mature fish; pectoral, ventral, and anal with white margins. Lakes of North Wales (Llanberris). Considered by Mr Day as a variety of S. alpinus.

S. grayi, Giinther (Proc. Zool. Soc, 1862, p. 51). D. 13 ; A. 12 ; P. 13-14 ; V. 9 ; L. lat. 125 ; Vert. 60 ; Ca3c. pyl. 37. Sides with scattered light-orange-coloured dots ; belly uniform silvery whitish, or with a light-red shade ; fins blackish. Lough Melvin, Ireland. Considered by Mr Day as a variety of S. alpinus.

8. colii, Giinther (Proc. Zool. Soc, 1863) (Cole's Charr, Couch, Fish. Brit. Isles). D. 14; A. 12 ; P. 13 ; V. 9; L. lat. 160; Vert. 63 ; Case. pyl. 42. Bluish black above; sides silvery with scattered light-salmon-coloured dots ; belly reddish ; fins black, the anal and the paired fins with a reddish tinge, the anal and ventrals with a narrow whitish margin. A small species 7 to 8 inches long from Loughs Eske and Dan, Ireland. Considered by Mr Day as a variety of S. alpinus.

The above are all the British species.

S. umbla, L. (Syst. Nat.), Cuv. and Val. D. 12 ; A. 12-13 ; P. 14 ; V. 9 ; L. lat. 200 ; Vert. 65 ; Ca3c. pyl. 36. Commonly called in French Ombre Chevalier. Lower parts whitish or but slightly tinged with red. Lakes of Constance, Neuchätel, and Geneva. Considered by Mr Day as identical with S. alpinus. Other species have been described from lakes in Europe and Asia, but are imper-fectly known ; for an account of them see Giinther's Catalogue.
The following American species of Charr is one of those cultivated by the American Fish Commission :—

S. (Salvelinus) fontinalis, Mitch. (Trans. Lit. and Phil. Soc, New York, i. p. 435), Cuv. and Val. (xxi. p. 266) (Brook Trout). B. 12; D. 12; A. 10; L. lat. 200; Case. pyl. 34. No median series of teeth along the hyoid bone. Praoperculum short in longitudinal direction, with the lower limb very indistinct. Rivers and lakes of British North America, and of the northern parts of the United States. Introduced in Britain.

2. Of the genus Osmerus only three species are described in the Brit. Mus. Cat., one of which is British :—

Osmerus eperlanus, Lacep., Linn, (the Smelt; Fr., iperlan; Scotch, Sparling or Spirting). B. 8 ; D. 11 ; A. 13-16 ; P. 11 ; V. 8 ; L. lat. 60-62; L. transverse TI ; Case. pyl. 2-6 ; Vert. 60-62. Height of body much less than length of the head, which is a quarter or two-ninths of the total length to base of caudal fin. Snout pro-duced. Vomerine teeth and anterior lingual teeth large, fang-like ; posterior mandibular teeth larger than the anterior ones, which form a double series, the inner series containing stronger teeth than the outer one. Back transparent, greenish ; sides silvery. Adult size 10 or 12 inches. Coasts and numerous fresh waters of northern and central Europe.

Osmerus viridescens, Lesueur, another species scarcely distinct from 0. eperlanus, but with scales a little smaller, occurring on the Atlantic side of the United States.

Osmerus thaleichthys, Ayres, occurs abundantly in the Bay of San Francisco.

3. Of Coregonus forty-one species are described in the Brit. Mus. Cat. Four species are found in Britain :—

C. oxyrhynchus, Kröyer, Linn., Cuv. and Val. (xxi.). Called the Houting in Holland. B. 9 ; D. 14 ; A. 14-15 ; L. lat. 75-81 ; L. transverse tit; Vert. 58. Snout produced, with the upper jaw protruding beyond the lower, and in adult specimens produced into a fleshy cone. Length of the lower limb of operculum 1J to 1J times that of the upper. Pectoral as long as the head without snout. Found on coasts and in estuaries of Holland, Germany, Denmark, and Sweden. Captured recently (three specimens only) in Lincolnshire, near Chichester, and at the mouth of the Medway.

C. clupeoides, Lacepede ; C. pennantii, Cuv. and Val. (the Gwy-niad of Lake Bala, Schelly of Ullswater, Powan of Loch Lomond; sometimes called the Freshwater Herring). B. 9; D. 14-15; A. 13-16; L. lat. 73-90; L. transverse A; Case. pyl. 120; Vert. 38/20. Snout with upper jaw not produced. Pectoral larger than the head. Fins black or nearly so. Lakes of Great Britain.
C. vandesius, Richards (Faun. Bor. Amer.); C. albula, Cuv. and Val. (the Vendace). D. 11 ; A. 13 ; V. 11 ; L. lat. 68-71 ; L. transverse ^ > Vert. 56. Castle Loch, Lochmaben in Dumfries-shire.

C.pollan, Thompson (Proc Zool. Soc, 1835), Cuv. and Val. (the Pollan). D. 13-14; A. 12-13; V. 12; L. lat. 80-86; L. transverse X9X; Vert. 60-61. Two jaws of same length. Teeth if present very minute. Bluish along the back, silvery along the sides and beneath. Usual length of adults 10 to 11 inches, maximum 13 inches. Ireland, in Loughs Ncagh, Erne, Dcrg, Corrib, and the Shannon.

Thirty-seven species of Coregonus have been distinguished besides these four. Some are migratory ; but the greater number are inhabitants of large lakes. The anadromous species are confined to the Arctic Sea, and the greater number belong to the coast and rivers of Siberia. Several distinct species occur in the lakes of Sweden ; a few are found in the lakes of Switzerland and central Europe. C. hiemalis is peculiar to the Lake of Constance. Several species inhabit the great freshwater lakes connected with the river St Lawrence of North America, and the lakes farther to the north. One of these is cultivated by the American Fish Commission :—

Coregonus clupeiformis, Mitchell, Dekay (New York Fauna, Fish), Cuv. and Val., Agassiz (Lake Superior) (the Shad Salmon, Freshwater Herring, Whitefish). D. 12; A. 14 ; L. lat. 76-77 ; L. transverse T8¥. The snout is pointed, and there is an appendage to the ventral fin which is half as long as the fin itself. Length of adult 11 to 13 inches. Lakes Erie and Ontario.

4. Only one species of Thymallus occurs in the British Islands :—

Thyinallus vulgaris, Nilsson; Thymallus vexillifer, Cuv. and Val. (the Grayling; French, VOmbre; Italian, Témelo). B.7-8 ; D. 20-23 ; A. 13-16 ; P. 16 ; V. 10-11 ; L. lat. 75-85 ; L. transverse ' *-'sec' P^' ^' Vert. 39/22. Length of head two-ninths or one-fifth of total length to base of caudal; posterior dorsal rays somewhat produced in adult. Grows to 15 inches in length. A freshwater fish, common in many of the rivers of England, introduced into some of those of southern Scotland ; absent from Ireland. It is widely distributed in central and northern Europe, occurring in Lapland, Sweden, Lake of Constance, the Isar, and the Danube. Adult size about 15 inches.

Thymallus xliani, Cuv. and Val. (OvuaWos, Ml., xiv. 22), occurs in Lago Maggiore. One species has been described from Siberia, and two are known inhabiting Lake Michigan and the waters of British North America.

5. Of Argentina four species are described in the Frit. Mus. Cat., namely:—Argentina situs, Nilsson, occurring off the north-west coast of Norway, Argentina sphyrmna, L., from the Mediterranean, Argentina hebridica, Nilsson, found on the coasts of Norway and Scotland, and Argentina lioglossa, Cuv. and Val. According to Mr j Day, two of these, A. sphyrmna and A. hebridica are identical, the species ranging from the coast of Norway and east and west shores of Scotland to the Mediterianean. The following is the formula of A. hebridica, Nilsson, according to Giinther:—D. 9-11 ; A. 13 (12); P. 13-14 ; V. 11 ; L. lat. 52-53 ; Caec. pyl. 14-20 ; Vert. 52. The scales with minute spines.

6. The species of Oncorhynchus are all anadromous, and are confined to American and Asiatic rivers flowing into the Pacific. 0. quinnat, Richardson = 0. chouicha occurs in the river Sacra-mento, and is cultivated by the American Fish Commission.

7. 8. For Braehymystax and Luciotrutta, see p. 221 above.

9. Plecoglossns comprises small aberrant freshwater species
abundant in Japan and the island of Formosa.

10. Retropinna contains but one species, R. richardsonii, which is known as the New Zealand Smelt. It is common on the coasts of New Zealand, ascending estuaries. Like Osmerus eperlanus, it is landlocked in fresh water in some localities.

11. 12. The species of Hypomesus and Thaleichthys occur on the Pacific coast of North America. Thaleichthys pacificus, Girard, is caught in vast numbers in the neighbourhood of Vancouver Island; it is extremely fat, and is used as a torch when dried, and also as food. It is called locally the Eulachan or Oulachan.

13. Of Mallotus only one species is described by Giinther:—
Mallotus villosus, Cuv. and Val., Miill. (the Capelin ; French, Capelan). B. 8-10 ; D. 13-14 ; A. 21-23 ; P. 18-20 ; V. 8 ; Case, pyl. 6 ; Vert. 68. Brownish on the back, silvery on the sides. Operculum silvery with minute brown dots. Shores of Arctic North America and of Kamchatka.

14. Of the genus Salanx two species are known:—Salanx chinensis, Giinther, Osbeck, which is common on the coast of China and called " Whitebait" at Macao, and Salanx microdon, Bleeker, from the rivers of Jeddo.

15. Microstoma.—M. rotundatum, Risso, is marine and occurs in the Mediterranean ; it is not anadromous. It is the only species of the genus known, unless the Microstomia gronlandicus, described by Reinhardt, from the Sea of Greenland, really belongs to this genus.

16. For Bathylagua, see p. 222 above.





Life History of the Salmon and Allied Species.

Up to a period not many years past, when our knowledge of the breeding and life history of the salmon and kindred species was based entirely on desultory observations of the fish in their natural conditions, there existed .a great deal of uncertainty and diversity of opinion on the subject. Within the last twenty or thirty years the extensive practice of salmon-culture has removed nearly all obscurity from the phenomena, and the history of Salmonoids is now more accurately known than that of most other fishes.

The salmon proper, Salmo salar, breeds in the shallow running waters of the upper streams of the rivers it ascends. The female, when about to deposit her eggs, scoops out a trough in the gravel of the bed of the stream. This she effects by lying on her side and ploughing into the gravel by energetic motions of her body. She then deposits her eggs in the trough ; while she is engaged in these operations she is attended by a male, who sheds milt over the eggs : as the female extrudes them, fertilization being, as in the great majority of Teleostei, external. The parent fish then fill up the trough and heap up the gravel over the eggs until these are covered to a depth of some feet. The gravel heap thus formed is called a "redd." The period of the year at which spawning takes place in the British Isles, and in similar latitudes of the northern hemi-sphere, varies to a certain extent with the locality, and in a given locality may vary in different years ; but, with rare exceptions, spawning is confined to the period between the beginning of September and the middle of January.

The eggs of Salmo solar are spherical and non-adhesive ; they are heavier than water, and are moderately tough and elastic. The size varies slightly with the age of the parent fish, those from full-sized females being slightly larger than those from very young fish. According to rough calculations made at salmon-breeding establishments, there are 25,000 eggs to a gallon; the diameter is about a quarter of an inch. It is usually estimated that a female salmon produces about 900 eggs for each pound of her own weight; but this average is often exceeded.

The time between fertilization and hatching, or the escape of the young fish from the egg-membrane, varies considerably with the temperature to which the eggs are exposed. It has been found that at a constant temperature of 41° F. the period is 97 days; but the period may be as short as 70 days and as long as 150 days without injury to the health of the embryo. It follows therefore that in the natural conditions eggs deposited in the autumn are hatched in the early spring. The newly hatched fish, or "alevin," is provided with a very large yolk-sac, and by the absorption of the yolk contained in this the young creature is nourished for some time ; although its mouth is fully formed and open, it takes no food. The alevin stage lasts for about six weeks, and at the end of it the young fish is about 1J inches long. During the next period of its life the young salmon is called a " parr," and is dis-tinguished by the possession of a number of dark transverse marks along the sides, known as "parr marks." These marks occur in the young stage of many species among the Salmonidss. The parr doubles its length in about four months.

The great majority of parr remain in fresh water for two years after hatching, at the end of which time they are about 8 inches in length. The second spring after they are hatched they develop a coating of bright silvery scales which completely conceals the parr marks, and they pass into a stage in which they are known as "smolts." The smolt is similar to the adult salmon in all respects except size, and the young salmon, as soon as the smolt stage is reached, migrates down the rivers to the sea.

The above facts have been established within recent years by accurate observation and experiment. Not very long ago it was a disputed question whether the parr was the young salmon or a distinct species of fish. That the former view was correct was first experimentally proved by Mr John Shaw, gamekeeper to the duke of Buccleuch, Drumlanrig, Dumfriesshire, who in 1833 isolated several parrs in a pond, and found that in April 1834 they changed into smolts ; an account of this experiment was published in the Transactions of the Royal Society of Edinburgh. The question is now of merely historical interest, for at the present time large num-bers of parr are hatched at various fish-hatching establishments every season. By observation at these establishments, the know-ledge of the history of the parr and the migration of the smolt which had been gained by the study of the fish in their natural conditions has been rendered more accurate and complete.1 It has been conclusively ascertained that some parr become smolts and migrate to the sea in the spring following that in which they were hatched, while the great majority remain in the parr stage until the second spring, and a few do not attain to the smolt condition until the third year. The male parr when only 7 or 8 inches in length is often sexually mature, the milt being capable of fertilizing the ova of an adult female salmon.

The migration of smolts to the sea takes place in all rivers at about the same time of the year, viz., between March and June. Sometimes the smolts are observed descending in large shoals. Formerly angling for the descending smolts was a recognized sport, but their capture is now illegal. It is the opinion of the most competent authorities that the smolts increase with wonderful rapidity in size and weight when they reach the sea, and then return to the rivers after a few months, during the same year, as "grilse," which name is given to sexually mature salmon up to a little over 5 lb in weight. It is surprising that a smolt weighing only a few ounces should increase to 3 or 4 or even 6 lb in about three months. Nevertheless it has been proved by actual experiment that this is the fact. At Stormontfield, in May 1855, 1300 smolts were marked by cutting off the adipose fin, and 22 of these
1 The first important series of experiments on the growth and life history of the salmon was made at the salmon-hatchery of Stormontfield near Perth in 18C2 and some previous years. The results are detailed.in a work entitled Stormont-jield Experiments were recaptured the same summer as grilse, weighing from 3 lb upwards. It might be supposed that some smolts do not return as grilse till the summer following the year of their descent, the time of their stay in the sea being variable, as is the period spent by parr in the rivers. But all the evidence is against this supposi-tion ; grilse never commence ascending till late in summer; if they had been more than a year in the sea, some would probably ascend early in the season, as do the larger salmon. At the same time it must be borne in mind that a fish which remained in the sea a year after descending as a smolt might not be recognized as a grilse, having reached the size of a small salmon.

The grilse, after spawning in autumn, return again to the sea in the winter or following spring, and reascend the rivers as mature spawning salmon in the following year. Both salmon and grilse after spawning are called "kelts." The following recorded experi-ment illustrates the growth of grilse into salmon :—a grilse-kelt of 2 lb was marked on March 31, 1858, and recaptured on August 2 of the same year as a salmon of 8 lb.

The ascent of rivers by adult salmon is not so regular as that of grilse, and the knowledge of the subject is not at the present time complete. Although salmon scarcely ever spawn before the month of September, they do not ascend in shoals just before that season; the time of ascent extends throughout the spring and summer. A salmon newly arrived in fresh water from the sea is called a clean salmon, on account of its bright, well-fed appearance ; during their stay in the rivers the fish lose the brilliancy of their scales and deteriorate in condition. The time of year at which clean salmon ascend from the sea varies greatly in different rivers ; and rivers are, in relation to this subject, usually denominated early or late. The Scottish rivers flowing into the German Ocean and Pentland Firth are almost all early, while those of the Atlantic slope are late. The Thurso in Caithness and the Naver in Suther-landshire contain fresh-run salmon in December and January ; the same is the case with the Tay. In Yorkshire salmon commence their ascent in July, August, or September if the season is wet, but if it is dry their migration is delayed till the autumn rains set in. In all rivers more salmon ascend immediately after a spate or flood than when the river is low, and more with the flood tide than during the ebb.

In their ascent salmon are able to pass obstructions, such as water-falls and weirs of considerable height, and the leaps they make in surmounting such impediments and the persistence of their efforts are very remarkable. In a great many rivers anadromous Salmon-oids have been excluded from the upper reaches by artificial obstructions, such as dams and weirs, constructed for the purpose of utilizing the water of the stream, or to obtain water power, or simply to facilitate the capture of the fish. Other rivers have been rendered uninhabitable to salmon by pollutions. The state of the Thames within the boundaries of London has since the beginning of the present century excluded Salmonoids entirely from the river; but every season salmon and grilse are taken in or near the Thames estuary, and there is no doubt that if the water could again be rendered moderately clear, and if fish-ways were provided at the impassable weirs, the upper waters of the Thames would again be frequented by salmon and migratory trout.

The life history of Salmo trutta and S. cambricus is very similar to that of Salmo salar. The river trout, S. fario, makes a redd in the shallower parts of streams in the same manner as the salmon, the only difference being that the mound of gravel forming the redd is smaller, the egg lying from one to two feet below the surface. The breeding period of the trout varies in different rivers, within the limits of September and March.1 The number of eggs pro-duced by each female is about 800 for every pound of the parent's weight; about 40,000 of the eggs make a gallon, so that they are considerably smaller than those of S. salar. The trout of Loch Leven, S. levenensis, ascend the streams feeding the loch, in order to spawn, at the end of September and beginning of October. The habits of other species of lake trout are similar to those of S. levenensis.

The charrs differ from lake trout in the fact that they do not ascend streams in order to spawn, but form their redds in the gravelly shallows of the lakes they inhabit. The spawning period of the eharr of the Cumberland lake district is from the beginning of November to the beginning of December. The eggs of the charr have been found to hatch in from 60 to 90 days, the great majority in 70 days, at an average temperature of 40° F. The American species, S. fontinalis, breeds at about the same time as S. fario; its eggs are only half the size of those of the latter.

The smelt, O. eperlanus, is a gregarious fish and exhibits regular migrations in most estuaries. It is common in the Solway, the Firth of Forth, the rivers of Norfolk, and the estuary of the Thames. In most places where it is found it remains in the fresh and brackish water from August until May, spawning about the month of April, and afterwards descending to the sea for the

The average period between fertilization and hatching, as ascertained at Howietoun, is at 44"°1—Salmo fario, 71 days; S. levenensis, 72 ; S. fontinalis, 73; S. salar, 77. summer. At Alloa on the Forth smelts are taken in large numbers by seine nets in spring, before and during the spawning period. There is a regular fishery for them at the same season on the Solway Firth and in Norfolk. The food of the smelt consists chiefly of young fish, especially young herrings, and crustaceans. The eggs are small, yellowish in colour, and adhesive, not adhering by the surface merely as is the case with those of the herring, but each egg possessing a short thread the end of which becomes attached to planks, stones, or other solid objects in the water. According to Mr Day the eggs are deposited near the high-water mark of spring-tides, so that they must be exposed to the air during tha ebb. The smelt when in the sea is largely eaten by the picke 1 dog-fish (Acanthias vulgaris). The species is absent from the southern coast of England and from Ireland, the smelt recorded as occurring on those coasts being probably the atherine (Atherina), often called the sand-smelt. O. eperlanus is abundant on the coast of Finland, and also is common there in freshwater lake t, in which it remains all the year round. It is also common on the Atlantic coast of France. It is of interest to note that the smelt in Britain and on other coasts, when not confined to fresh water, is, in its migration, intermediate between anadromous Salmonidm, which ascend to near the sources of rivers, and such fish as the herring, which approach the shore to spawn but do not usually enter rivers. The smelt as a rule ascends estuaries only as far as the region of brackish water.

The various species of Ooregonus resemble the charr in their habits, spawning in the autumn in the shallows of the lakes they inhabit ; their ova are small, and, as mentioned in PISCICULTURE (q.v.), are non-adhesive and of almost the same specific gravity as fresh water, so that they are semi-buoyant.

The grayling, Thymallus vulgaris, is in Britain exclusively fluviatile ; in Scandinavia it is found also in lakes. It is met with chiefly in clear streams with sandy gravels or loamy beds. It was introduced not many years ago into the Tweed by the marquis of Lothian, and thrives there. It is absent from the Thames, but is common in most of the rivers of England and "Wales —e.g., the rivers of Yorkshire, the Severn, and the Wye. It is absent from Ireland. It feeds on insects and their larva?, crustaceans, and small molluscs. It breeds in April and May, depositing its ova on the surface of the gravel in the shallows, not in a redd. The ova are smaller than those of the trout, and vary in colour from white to deep orange, and they hatch from the twelfth to the fourteenth day after extrusion. The fry grow to 4 or 5 inches in length by August, and by the following autumn to 9 or 10 inches.

Salmon Fishery Legislation.

In England and Wales the common law is that every person has an equal right to fish for salmon in the sea and in navigable tidal rivers, while the proprietors of the soil on the banks of rivers which are not navigable have the exclusive right of fishing in them. The erection of stake-nets, or other fixed engines for the capture of salmon in estuaries or on the sea-coast is necessarily incompatible with the maintenance of the public right of fishing, and has therefore from very early times been regarded as illegiti-mate. There has consequently been a constant conflict between legislation and private interest over this point. By Magna Charta all fishing weirs were abolished except on the sea-coast, but the object of this seems to have been rather the protection of the freedom of navigation than the advantage of the salmon fisheries or. the maintenance of a public right. In later times fixed engines were repeatedly declared illegal and their erection prohibited by statute. Finally in 1861 they were definitively abolished in all cases except where legal right to maintain them could be conclusively proved. The Salmon Fishery Act of 1861, of which the prohibition just referred to was one of the clauses, was based upon the report of a royal commission appointed in 1860 to inquire into the condition of the salmon fisheries, and it forms the basis of the regulations at present in force, all previous legislation being by it expressly abolished and superseded. It prohibited the capture of unclean and unseasonable salmon, made a uniform close season for England and Wales, ordained a weekly close season of forty-two hours, provided for the erection of fish-passes and regulated the use of fishing weirs on non-navigable rivers, vested the central authority of the salmon fisheries in the Home Office, and provided for the appointment of inspectors. In 1863 an Act was passed prohibiting the exportation of salmon during the close time. In 1865, as it was found useless to legislate without machinery to enforce the law, an Act was passed to constitute fishery districts under the control of local boards of conservators appointed by the magistrates in quarter-sessions. These boards were empowered to enforce a licence duty on fishing implements used in public waters. One or two minor salmon fishery Acts were passed in succeeding years, but the next important piece of legislation on the subject was the Act of 1873, the two most important provisions of which are (1) that fishermen in public waters or every £50 of licence duty which they pay elect a member of the local 1)08161 of conservators, and (2) that each board of conservators may make bye-laws for the regulation and improvement of the fisheries within its own district. The annual close time for salmon in England and Wales at present for nets commences Aug. 14-Sept. 30 and closes Feb. 2-April 1, varying in different districts within the limits given ; for rods the close time is Sept. 30-Nov. 29 to Feb. 1-May 1. The law as regards close time for fixed engines was amended in 1879. The method of fishing followed in the English and Welsh estuaries is in consequence of the above course of legislation that of sweep-nets worked from shore by boats ; a licence duty has to be paid for each net, and stake-nets along the coast are very rare. An inspector of salmon fisheries appointed by the Home Office reports annually.

In Scotland the laws regulating salmon fisheries differ in some important particulars from those of England. There is no public right of salmon fishing,—all salmon fishings, whether in rivers, estuaries, or the narrow or territorial seas, belonging either to the crown or the grantees of the crown. Movable nets only can be used in rivers and in estuaries ; but fixed nets—that is, stake-, fly-, and bag-nets—may be used outside the estuaries of rivers and on the shores of the sea. The principal Acts regulating the Scotch salmon fisheries are the Acts of 1862 and 1868, the Tweed Fisheries Acts of 1857 and 1859, and the Solway Act of 1804. But some other Acts are still in force ; and, to simplify existing legislation, a consolidation Act is much needed. There is an annual close time of 168 days, except on Tweed, where it is 151, and a weekly close time of 36 hours, from 6 in the evening of Saturday until 6 on Monday morning. There is an extension of time for angling aftei the nets are off, varying from 6 weeks to 3 months. The construc-tion and use of cruives, dams, mill-lades, water-wheels, and the meshes of nets are regulated ; and Scotland is divided into fishery districts, about one-third of which have district boards. In 1882 a Fishery Board for Scotland was constituted, which has the general superintendence of the salmon fisheries. An inspector of salmon fisheries was likewise appointed by the home secretary, who has since visited all the salmon rivers in Scotland and reported on them to the Fishery Board.

The common law regarding the right of fishing in the sea and navigable rivers and waters in Ireland is the same as that of England. The principal statute regulating the Irish fisheries is that of 1863. There are boards of conservators, clerks, water bailiffs, and licence duties, as in England. The weekly close time is 48 hours. The annual close time for nets is not less than 168 days, but the inspectors may vary the periods at which it com-mences and ends. The close season for angling is from 1st November to 1st February exclusive. There are three inspectors of salmon fisheries, who make annual reports to the lord lieutenant of Ireland.

Introduction of Species to New Areas by Human Agency.

Within the past few years, since great activity has been ex-hibited in pisciculture generally, and especially in the culture of Salmonidx, various experiments have been made in the trans-portation of eggs or young fry of valuable species from their native habitats to distant parts of the world. The American so-called brook trout, S. fontinalis, has been imported somewhat largely into Britain by various salmon fishery proprietors. It thrives well in various places in England, Scotland, and Wales where it has been set free, —for example, in Norfolk rivers, near Guildford in Surrey, and in the stock ponds at Howietoun.
In Nature, July 16, 1885, an account was given of the introduc-tion of the fry of the American landlocked salmon (S. salar, var. sebago) to the upper waters of the Thames. Eggs of S. namaycush, S. sebago, S. fontinalis, and Coregonus albus have been successfully forwarded from the hatcheries of the American Fish Commission to the Deutsche Fischerei-verein in Berlin, and to the Société d'Acclimatation at Paris.

The common trout of Britain, S. fario, was introduced with complete success into Tasmania nearly twenty years ago by Frank Buckland, and is now abundant in the Tasmanian streams, although it is reported to be much less valued as food there than at home. From Tasmania the eggs were transported to the rivers in Otago, New Zealand, where they also thrive and breed (see Trans. of Otago Institute, 1878). In 1866 Mr Francis Day introduced the fry of the same species into the rivers of the table-land of the Nilgiris in the neighbourhood of Madras. The experiment on this occasion failed, but two years later the establishment of the species in the district in question was successfully accomplished by Mr M'lvor, who imported the fry from Scotland.

Salmon Culture.

For the artificial culture of Salmonoids the reader is referred to' the article PISCICULTURE. The following account of the salmon and trout hatcheries in Scotland is abridged from a paper read before the Scottish Fisheries Improvement Association in Edin-burgh, 26th November 1884, by J. Barker Duncan, the honorary secretary to the Association.

The principal institution of its kind in Scotland at present is the Howietoun Fishery, belonging to Sir J. Gibson Maitland, who commencedit in 1873. Howie-toun is about four miles from Stirling. The establishment contains thirty-two fish ponds and a large hatching-house; there are also four ponds at Cruigend, and one of 9 acres at Goldenhove, where fish are reared to their adult condition. The hatching-boxes are of wood, and the eggs are kept during development on glass grilles. The water supply is abundant, about a million gallons of spring water flowing through the ponds every twenty-four hours. The eggs hatched in greatest numbers are those of the Loch Leven trout, but Salmo salar and the common trout (Salmo fario) are also extensively reared. The American brook trout, /ST. fontinalis, is also cultivated. More than ten millions of ova are annually treated at this hatchery. In 1884 ninety thousand young fish were distributed to various parts of Great Britain and Ireland, and two consignments of trout and one of salmon ova were successfully sent to New Zealand.

The Solway Fishery, belonging to Mr Joseph J. Armistead, was established in 1881, to supersede the Treutdale Fishery near Keswick, Cumberland. It is situ-ated near the Solway in Kirkcudbrightshire. Various kinds of trout and charr, salmon and sea-trout, grayling, and other freshwater fish are bred. The hatching-house is fitted to hatcti about a million ova. Small and large quantities of ova are supplied to applicants for purposes of stocking or for experiments in fish culture.

The Stormontfield Ponds were established in 1853 by proprietors of Tay fisheries. They are situated about 5 miles above Perth on the Tay and occupy about 2 acres of ground. The Stormontfield experiments above referred to were carried out at these ponds under the direction of Mr Robert Buist. The estaolishment is now almost superseded by the Dupplin Hatchery, but is still used to some extent. The hatching-boxes, 360 in number, are in the open air, and the eggs are placed on gravel at the bottom of the boxes ; a larger percentage of loss occurs with this system than when glass grilles are used. Two of the ponds at Stormontfield are stocked with parr from the Dupplin Hatchery, about 20,000 being placed in them in 1884 ; the parr are fed with ground liver, and are liber-ated in the river and its tributaries when two years old.

The Dupplin Hatchery was instituted in 18S2 by the Tay district board at Newmill, Dupplin Castle, on the river Earn, a tributary of the Tay. The hatching-house is supplied with spring water, and contains about 300,000 ova. The glass grille system is adopted here, and the fry are liberated in the Tay and its tributaries when about forty days old.

There is a hatchery for Loch Leven trout erected in 1883 by the Loch Leven Angling Association, situated about 800 yards from the loch, beside a small stream. In the season of 1884-85 about 220,000 eggs were laid down. The fry are turned into the feeders of the loch five or six weeks after hatching. Before the erection of this hatchery Loch Leven was several times stocked with fry from the Howietoun Fishery. The great effect of stocking on the produce of Loch Leven is shown by the following figures :—in 1884 over 15,000 trout were taken in the loch during the season from April to September; during the preceding ten years the lake had been supplied with some thousands of fry in five several seasons; previous to 1874 no attempt at stocking had been made, and in that year the total catch was about 5000.

In May 1884 the Linlithgow Palace Loch Hatchery was opened by its proprietor, Mr A. G. Anderson, fish merchant, Edinburgh, who holds a lease of the loch for angling purposes from the crown. The hatchery is intended chiefly to stock the loch, and is capable of containing about 600,000 ova. Experiments on the cultiva-tion of Salmo salar, var. sebago, from America, are also to be made here.

A private hatchery belonging to the marquis of Ailsa, capable of hatching about 250,000 ova, is situated at Culzean in Ayrshire. Salmon ova are obtained from the rivers Doon, Stinchar, and Minnock, and the fry turned again into those rivers when about six weeks old. Chair, S. fontinalis, and Loch Leven trout are also hatched to stock the hill lochs of the estate of Culzean. Accord-ing to Mr Young the number of salmon in the Doon has been considerably increased by the artificial stocking from this establishment.

Another private hatchery, with a capacity of 50,000, is maintained on the Loch-buy estate, Isle of Mull, for the purpose of stocking the rivers and lakes on the property.
The Aberdeen Hatchery was established in Aberdeen by the district boards of the rivers Dee and Don. From 15,000 to 20,000 fry are hatched here every year and are conveyed 10 to 40 miles up the rivers Dee and Don and then liberated.

Various proprietors in Scotland have at various times erected small hatching-houses on the rivers of their estates for the purpose of stocking, but, these have not been maintained. The above-mentioned are the only salmon-rearing estab-lishments of any importance at present in operation in Scotland.

Salmon Disease.

During the last few years salmon in a great many rivers have been observed to be suffering from an epidemic cutaneous disease from which large numbers have died. So far as is known this disease in its epidemic form is quite a new phenomenon ; there can be little doubt that it must have occurred as a sporadic affection in former times, but it seems on the other hand probable that such mor-tality among salmon as has taken place in some recent seasons must have attracted attention if it occurred, even when accurate observation was rare. The disease was first noticed in 1877 in the Esk and the Nith, flowing into the Solway Firth, and since then it has destroyed very large numbers of salmon in almost every river in Britain. The disease consists in ulcerations of the skin, which begin at one or several spots on the head and body, and ultimately extend to the whole surface of the fish. The diseased parts of the skin are found when examined to be covered with a fungoid growth, with the mycelium of a fungus consisting of plaited hyphse which extend into and ramify through the tissue of the derma and epidermis, causing the cells to die, until the super-ficial tissues decay and slough off, and inflammation and bleeding are produced in the deeper and surrounding parts. It is certain that the injury to the skin and flesh of the salmon is caused by the fungus. If a section of the edge of an affected spot be made, and examined microscopically, the cells are seen to be perfectly normal and healthy beyond the region to which the hyphse extend, and the growing points of the hyphse are seen to be penetrating between and distorting these uninjured cells. It is evident therefore that the morbid alteration of the tissues follows the attack of the hyphse and does not precede it. The external superficial part of the mycelium covering a diseased spot of the skin bears the fructification of the fungus. This consists of zoosporangia, which are the enlarged blind terminal parts of certain of the hyphae, that stand out perpendicular to the surface of the mycelium. Each zoosporangium contains a multitude of spherical spores. These spores are of the kind technically called zoospores, each on its escape from the sporangium moving about actively by means of two vibratile cilia. The zoosporangium emits the zoospores by an aperture at its end, and when it has emptied itself the hypha begins to grow again at the base of the empty membrane and sends up through the cavity of the old zoosporangium a new sprout which becomes a second spore capsule. This feature is character-istic of the genus Saprolegnia, belonging to the Oosporem, various kinds of which are well known to botanists ; they usually occur in dead insects or other invertebrate animals in water: the dead bodies of the common house-fly when in a sufficiently moist place almost invariably produce a luxuriant crop of Sapro-legnia. The commonest species of Saprolegnia is S. ferax, and the salmon fungus has usually received the same name, as though it were a proved fact that it was identical with that species. But the species of a Saprolegnia can only be ascertained from the characters of its oosporangia, which are quite different from the zoosporangia and are produced much more rarely, and whose contents, the oospores, are fertilized by the contents of simultaneously produced antheridia. Mr Stirling has observed the oosporangia of salmon fungus (see his papers in Proc. Boy. Soc. Ed., 1878 and 1879), but his description is not sufficient to put the identification of the species beyond a doubt. From Prof. Huxley's experiments it is evident that the salmon fungus may reproduce for very many generations without the appearance of oospores. The salmon fungus grows with great luxuriance on other animal substances. In a diseased salmon the fungus seems to be confined to the skin and not to give rise to bacteria-like bodies in the internal organs. What are the condi-tions which favour the infection of salmon in a river is a question to which at present no answer can be given. Until it is known under what conditions the Saprolegnia exists in a river before infecting the salmon, the conditions which favour or prevent salmon disease cannot be ascertained. The fungus may have its permanent nidus in decaying vegetable substances, but at present it has not been determined whether it is possible to cultivate the salmon Saprolegnia on vegetable matter; or the disease may be propagated sporadically among the fish, Salmonoids and others, which are permanent residents of the rivers ; or its abundance may depend on the amount of dead animal matter that is available for its nutrition. There is probably always some Saprolegnia in every river ; the secondary conditions which determine whether or not the fungus shall multiply on the anadromous salmon to such an extent as to cause an epidemic have yet to be ascertained.

Literature.—Albert Günther, Catalogue of Fishes in Brit. Mus., London, 1866, vol. vi. ; Id., Introduction to Study of Fishes, Edinburgh, 18S0; Francis Day, Fishes of Great Britain and Ireland, London and Edinburgh, 1880 to 1854, vol. ii. The following papers of the Conferences of the International Fisheries Exhibition, London, 1883, also contain valuable information:—"Fish Culture," by Francis Day; "Salmon Fisheries," by Charles S. Folger; "Culture of Salmonidae," by Sir James Maitland; "Salmon and Salmon Fisheries," by David Milne Home. For a most complete and valuable memoir on the salmon disease see the paper by Prof. Huxley, Quart. Jour. Mic. Sci., 1882. (J. T. C.)



The above article was written by: J. T. Cunningham, B.A., Fellow of University College, Oxford.