96 Salmonidas 



Alaska, and the valley of Mackenzie River have species of 

 black-spotted trout. There are few of these north of Sitka in 

 Alaska, although black-spotted trout are occasionally taken on 

 Kadiak and about Bristol Bay, and none east of the Rocky 

 Mountain region. If we are to follow the usage of the names 

 "salmon" and "trout" which prevails in England, we should 

 say that, in America, it is only these western regions which 

 have any trout at all. Of the number of species (about twenty- 

 five in all) which have been indicated by authors, certainly not 

 more than about 8 to 10 can possibly be regarded as distinct 

 species. The other names are either useless synonyms, or else 

 they have been applied to local varieties which pass by degrees 

 into the ordinary types. 



The Trout of Western America. In the western part of America 

 are found more than a score of forms of trout of the genus Salmo, 

 all closely related and difficult to distinguish. There are represen- 

 tatives in the headwaters of the Rio Grande, Arkansas, South 

 Platte, Missouri, and Colorado rivers ; also in the Great Salt Lake 

 basin, throughout the Columbia basin, in all suitable waters from 

 southern California and Chihuahua to Sitka, and even to Bristol 

 Bay, similar forms again appearing in Kamchatka and Japan. 



Among the various more or less tangible species that may 

 be recognized, three distinct series appear. These have been 

 termed the cutthroat-trout series (allies of Salmo clarkii), the 

 rainbow-trout series (allies of Salmo irideus), and the steel- 

 head series (allies of Salmo rivularis, a species more usually but 

 wrongly called Salmo gairdneri) . 



The steelhead, or rivularis series, is found in the coastwise 

 streams of California and in the streams of Oregon and Washing- 

 ton, below the great Shoshone Falls of Snake River, and north- 

 ward in Alaska along the mainland as far as Skaguay. The 

 steelhead-trout reach a large size (10 to 20 pounds). They 

 spend a large part of their life in the sea. In all the true steel- 

 heads the head is relatively very short, its length being contained 

 about five times in the distance from tip of snout to base of 

 caudal fin. The scales in the steelhead are always rather small, 

 about 150 in a linear series, and there is no red under the throat. 

 The spots on the dorsal fin are fewer in the steelhead (4 to 6 

 rows) than in the other American trout. 



