FISHES. 163 



soft character of tlie bones in the latter group, as compared with those of the large 

 trout, is one feature of their excellence as food. 



Comparing the steel-heads with the rainbow trout, we find no differences, 

 other than that the former is much larger in size, and has a larger mouth, and its cau- 

 dal is truncate instead of forked. But the tail becomes more truncate, and the mouth 

 larger with age in all species. If a rainbow trout were to reach the size of the steel- 

 head, it ought to acquire characters similar to those of the latter species. Conversely, 

 unless the rainbow trout are young steel-head, the young of the latter species is 

 unknown. It is my belief that the steel-head is simply the large rainbow trout which 

 has lived in the sea, and ascended the river to spawn. If this be true, Salmo irideus 

 must be omitted from our lists, as identical with Salmo gairdneri. 



The most widely distributed, and in almost all respects the most important, of the 

 America black-spotted trout is the Salmo purpuratus, or, as we may call it, the 

 red-throated trout. This species has much smaller scales than the rainbow trout or 

 steel-head, the usual number in a longitudinal series being 150 to 170. Its mouth is 

 proportionately larger, and there is usually a narrow band of small teeth on the hyoid 

 bone at the base of the tongue. These teeth are always wanting in Salmo irideus, 

 gairdneri, and spilurus. The color in Salmo purpuratus is, as in other species, exces- 

 sively variable. In almost all specimens there is a deep-red blotch on the throat, 

 between the branches of the lower jaw, and the membrane connecting them. This I 

 have net found in other species, and as it seems to be constant in all varieties of Salmo 

 purpuratus, at all ages, it will furnish a good distinctive character. 



The red-throated trout is found in every suitable river and lake in the great basin 

 of Utah, in the streams of Colorado, Wyoming, and Montana, on both sides of the 

 Rooky Mountains. It is also found throughout Oregon, Washington, Idaho, British 

 Columbia, and Alaska, probably no stream or lake suitable for salmonoid life being 

 without it. In California the species seems to be comparatively rare, and its range 

 has not been well made out. Large individuals apparently analogous to the steel-heads 

 ai-e sometimes found in the mouth of the Sacramento. In Washington Territory and 

 Alaska this species often enters the sea. In Puget Sound, it is a common fish. 

 These sea-run individuals are more silvery and less spotted than those found in the 

 mountain streams and lakes. Numerous more or less tangible varieties of Salmo pur- 

 puratus occur, one of the most marked of which is the beautiful trout found in Lake 

 Tahoe, the finest of all the mountain lakes of the Sierra Nevada. 



The size of Salmo purpuratus is subject to much variation. Ordinarily four to six 

 pounds is a large size, but in certain favored waters, as Lake Tahoe, and the fjord bays 

 of the northwest, specimens of from 20 to 30 pounds are occasionally taken. 



No attempt has been made to transport this, the finest known species of black- 

 spotted trout, to eastern waters. The writer thinks it much better worthy of experi- 

 ment than the rainbow trout. The great variety of the waters in which it occurs 

 seems to promise a ready adaptation to other surroundings. 



The Rio Grande trout, {Salmo spilurus), is a large and profusely spotted trout 

 found in the head-waters of the Rio Grande, and in the mountain streams of the great 

 basin of Utah. Its scales are still smaller than those of the red-throated trout, to 

 which it bears much resemblance, and of which it is probably simply a local variety. 



The genus Hucho has been framed for the Huchen or Rothfisch {Ilucho hucJio), 

 of the Danube, a large salmon- differing from the genus Salmo in having no teeth on 

 the shaft of the vomer, and from the Salvelini, at least in form and coloration. The 



