24 Transactions of the Canadian Institute. [Vol. IX. 



in each, so that it becomes exceedingly difficult in some cases to determine 

 the proper position of individual fish, although typical forms are readily 

 distinguishable. One of these species is Salmo mykiss, the Cut-throat 

 or Rocky Mountain trout, which occurs in clear streams of the Pacific 

 coast all the way from Alaska to California. It derives its somewhat 

 disagreeably suggestive popular name of Cut-throat from a blotch of red 

 which is always present on the under surface of the head, between the 

 rami of the lower jaw. Those found in the coast-wise streams are ana- 

 dromous, periodically running up from the sea, but like the Atlantic salmon 

 it is also found as a permanent resident of various inland waters, the 

 Yellowstone trout, for example, being such a variety. A second species 

 is the Steel-head trout, 5. gairdneri, a splendid anadromous fish reaching 

 a weight of twenty pounds or more and ascending the coastal rivers from 

 California to British Columbia. It also occurs as a smaller land-locked 

 variety in the Okanagon, Kootenay and other British Columbian lakes. 

 Finally, the third species of this group is the S. iridens or Rainbow trout, 

 abundant in the mountain streams of the Coast range from Puget Sound 

 to California. It receives its specific and popular names from the brilliance 

 of its colouration, which otherwise resembles that of S. gairdneri, from 

 which, however, it may be distinguished by its smaller size (>^-6 lbs) and 

 by the larger size of its scales. These three forms are American repre- 

 sentatives of the European trout, 5. trutta, and it is to them that the 

 term trout is especially applicable. 



Distinguished from the genus Salmo by various structural peculiari- 

 ties, among which is the greater length of the anal fin, are the Pacific 

 Salmon, which have been assigned to the genus Oncorhynchus and of 

 which five species are recognized. The first and most important of these 

 is the 0. tschawytscha, variously known as the Spring, Quinnat, Chinook, 

 King, Columbia River and Sacramento River Salmon, a fish which forms 

 the main basis of the canning industry on the Columbia and Sacramento 

 Rivers, although it also occurs farther north in smaller numbers, being 

 taken in the British Columbian and Alaskan rivers and also in those of 

 northern China. In the Sacramento River it averages sixteen to eighteen 

 pounds in weight and in the Columbia as much as twenty-two pounds, 

 although much larger individuals, even up to seventy or one hundred 

 pounds, have been taken. Second in importance to the Spring salmon is 

 the Sockeye, 0. nerka, also known as the Fraser River or Blue-back 

 salmon or as the Red-fish, on account of the reddish hue assumed in the 

 breeding season. This is the most important species in the British Colum- 

 bia rivers and constitutes by far the greater portion of the pack of the 

 Canadian and Puget vSound canneries. In the Fraser River it averages 

 from six to seven pounds in weight. The three remaining species are of 



