FISHES. 163 



soft character of the bones in the latter group, as coiujtan-d with those of the large 

 irout, is one feature of their excellence as food. 



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

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

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

 larger with ago in all species. If a i-ainbow trout were to i-each 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 tiie 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 Subno fjairdneri. 



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

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

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

 steel-head, the usual number in a longitudinal series being 1.50 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. Tliese teeth are always wanting in Salmo irideus, 

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

 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 not found in other species, and as it seems to be constant in all varieties of Salmo 

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



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

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

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

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

 witliout 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 

 are sometimes found in the mouth of the Sacramento. In Washington Territory and 

 Alaska this species often enters tlie 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- 

 piiratus 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 p>urpiiratus is subject to much variation. Ordinarily four to si.x 

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

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



No attempt has been made to trans])ort this, the finest known species of black- 

 spotted trout, to eastern waters. Tiie writer thinks it much better worthy of ex])eri- 

 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 s|iotted 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 Ijcars nmch resemblance, and of which it is probably simply a local variety. 



The genus Hucho has been framed for the Iluchen or Rothfisch {JIucho hucho), 

 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 



