102 Salmonidz 
Cutthroat or Red-throated Trout.—This species has much 
smaller scales than the rainbow trout or steelhead, the usual 
number in a longitudinal series being r60o to 170. Its head is 
longer (about four times in length to base of caudal). Its 
mouth is proportionately larger, and there is always a narrow 
band of small teeth on the hyoid bone at the base of the tongue. 
These teeth are always wanting in Salmo irideus and rivularis 
in which species the rim of the tongue only has teeth. The 
color in Salmo clarkii is, as in other specjes, exceedingly variable. 
In life there is always a deep-red blotch on the throat, between 
the branches of the lower jaw and the membrane connecting 
them. This is not found in other species, or is reduced to a 
narrow strip or pinkish shade. It seems to be constant in 
all varieties of Salmo clark, at all ages, thus furnishing a good 
distinctive character. It is the sign manual of the Sioux Indians, 
and the anglers have already accepted from this mark the name 
of cutthroat-trout. The cutthroat-trout of some species 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 Rocky Mountains. It is also found throughout 
Oregon, Washington, Idaho, ‘British Columbia, the coastwise 
islands of southeastern Alaska (Baranof, etc.), to Kadiak and 
Bristol Bay, probably no stream or lake suitable for trout-life 
being without it. In California the species seems to be com- 
paratively rare, and its range rarely extending south of Cape 
Mendocino. Large sea-run individuals analogous to the steelheads 
are sometimes found in the mouth of the Sacramento. In Wash- 
ington and Alaska this species regularly 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. The size of Salmo clarkiz is subject to much variation. 
Ordinarily four to six pounds is a large size; but in certain 
favored waters, as Lake Tahoe, and the fjords of southeastern 
Alaska, specimens from twenty to thirty pounds are occasionally 
taken. 
‘Those species or individuals dwelling in lakes of considerable 
size, where the water is of such temperature and depth as in- 
sures an ample food-supply, will reach a large size, while those 
in a restricted ‘environment, where both the water and food are 
