A small aberrant form of Freshwater-Salmonoids abundantly found in Japan and the Island of Formosa.
Osmerus.—Body covered with scales of moderate size. Cleft of the mouth wide; maxillary long, extending to, or nearly to, the hind margin of the orbit. Dentition strong; intermaxillary and maxillary teeth small, much smaller than those of the mandible. Vomer with a transverse series of teeth, several of which are large, fang-like; a series of conical teeth along the palatine and pterygoid bones. Tongue with very strong fang-like teeth anteriorly, and with several longitudinal series of smaller ones posteriorly. Pectoral fins moderately developed. Pyloric appendages very short, in small number; ova small.
The “Smelt” (O. eperlanus) is common on many places of the coasts of Northern Europe and America. In the sea it grows to a length of eight inches; but, singularly, it frequently migrates from the sea into rivers and lakes, where its growth is very much retarded. That this habit is one of very old date, is evident from the fact that this small freshwater form occurs, and is fully acclimatised in lakes which have now no open communication with the sea. And still more singularly, this same habit, with the same result, has been observed in the Smelt of New Zealand (Retropinna richardsonii). The Smelt is considered a delicacy in Europe, as well as in America, where the same species occurs. Two other allied genera, Hypomesus and Thaleichthys, are found on the Pacific coast of North America, the latter being caught in immense numbers, and known by the name “Eulachon” and “Oulachan;” it is so fat, that it is equally used as food and as candle.
Mallotus.—Body covered with minute scales, which are somewhat larger along the lateral line and along each side of the belly; in mature males these scales become elongate, lanceolate, densely tiled, with free projecting points, forming villous bands. Cleft of the mouth wide; maxillary very thin, lamelliform, extending to below the middle of the eye. Lower jaw the longer, partly received between the maxillaries. Dentition very feeble; the teeth forming single series; only the teeth on the tongue are somewhat larger and disposed in an elliptical patch. Pectoral fins large, horizontal, with broad base. Pyloric appendages very short, in small number; ova small.
The “Capelin” (M. villosus) is found on the Arctic coasts of America and of Kamtschatka. It is caught in immense numbers by the natives, who consume it fresh, or dry it for use in the winter. Its length does not exceed nine inches.
Coregonus.—Body covered with scales of moderate size. Cleft of the mouth small; maxillary broad, short or of moderate length, not extending behind the orbit. Teeth, if present, extremely minute and deciduous. Dorsal fin of moderate length; caudal deeply forked. Ova small.
Fig. 293.—Coregonus oxyrhynchus.
Fig. 294.—Head of Coregonus oxyrhynchus.