42 VERTEBRATE ANIMALS OF THE UNITED STATES 



di Vomerine teeth not numerous and often deciduous; 



Atlantic salmon 2. Salmo. 



6.2 Vomerine teeth numerous and persistent; western 



trout 3. Trutta 



C2 Body spotted with gray 4. Cristivomer. 



bo Body spotted with red 5. Sahelinus. 



I. Oncorhynchus Suckley. Pacific salmon. Body elongate, com- 

 pressed, elliptical; mouth wide; during the breeding season, in the fall, 

 the snout of the male becomes distorted, both upper and lower jaw being 

 elongated, the former hooking over the latter, which is itself hooked at 

 the tip, the teeth become enormously enlarged, a fleshy hump develops 

 in front of the dorsal fin, and the flesh loses its pink color more or less 

 completely : 6 species ; north Pacific Ocean, ascending the rivers of both 

 America and Asia to spawn; the most valuable commercial fishes in the 

 country. The king salmon and blueback begin their run up the streams 

 generally the last of March and continue it until the spawning season 

 in the fall; the other species run only in the fall. The spring and 

 summer are when the most valuable catches are made and when the 

 fish are in the best condition. The fall catches are of far less commer- 

 cial value as the flesh of the fishes is then poor, dry and colorless. 

 The fish do not feed during the run, and most of them probably die 

 after spawning. The young salmon descend the stream to the sea 

 where they feed for a period of years, which for the king salmon is from 

 3 to 5 years, before arriving at maturity, when they migrate to the 

 spawning grounds. 



Key to the American Species of Oncorhynchus 



ai Gill-rakers short and comparatively few (20 to 25 in number); 



bi Tail with large oblong spots; scales very small 0. gorhuscha. 



bo Tail without large oblong spots. 



Ci Rays of dorsal fin 9; branchiostegals 13 or 14 0. keta. 



Co Rays of dorsal fin 11; branchiostegals 15 to 19 0. tschawytscha. 



C3 Rays of dorsal fin 10; branchiostegals 13 or 14 0. kisutch. 



ao Gill-rakers long and 30 to 40 in number 0. nerka. 



O. kennerlyi. 



0. gorhuscha (Walbaum). Humpback salmon. Weight up to 

 6 lbs.; color bluish, sides silvery; hinder part of back, adipose fin, and 

 tail with numerous oblong spots; rays of dorsal fin 11; anal 15; scales 

 very small, 200 in the lateral line; pyloric caeca 180: Pacific Ocean, 

 from central California northwards; common in Alaska; introduced to 

 the coast of Maine; of small food value. 



