134 



University of Washington Publications in Biology 



[Vol. 2. 



2b. Scales in fewer than 160 oblique rows crossing the lateral line, usually 

 about 120 to 153. Fig. 25. 



Dorsal fin 

 Parr narlcs jL Lateral. line 



Caudal 

 fin 



3a. 



4a. 



Fig. 21. A diagrammatic sketch of a trout to show the names 



of the parts that are used in differentiating species. Parr marks 



occur, with certain exceptions, in immature fish only. After 



Schultz and Hanson. Courtesy of the Washington Sportsman. 



Gill rakers comparatively short and few, 19 to 28 (rarely 29) in num- 

 ber on the 1st gill arch. 



Scales usually 19 to 26 (range 19 to 31) above, and usually 15 to 24 



(range 15 to 27 below, the lateral line; anal rays usually 13 to 15; 



gill rakers 7 or 8+11 to 13; pyloric caeca 150 to 180; young with 



rather faint small parr marks mostly above the lateral line. Range : 



Kamchatka to Alaska to San' Francisco. Marine and freshwater. 



Abundant. 



Chum Salmon. Dog Salmon. .. .33. Oncorhynchus keta (Walbaum) 



gill rilaj»nt» 



Fig. 22 



Fig. 22. This diagram illustrates the method employed in 

 counting the number of rays in the dorsal and anal fins. The 

 first two or three short, unsegmented rays closely crowded to- 

 gether are not counted. The first ray counted is unbranched 

 and extends nearly as far out as the first branched ray which 

 follows. The last ray is usually "double-branched" at the base 

 giving the superficial appearance of two rays, and hence is count- 

 ed as one ray. After Schultz and Hanson. Courtesy of the 

 Washington Sportsman. 



Fig. 23. This diagram illustrates the gill rakers on the first 

 gill arch, the latter located under the operculum. The gill rak- 

 ers, including all rudiments are always counted on the first gill 

 arch; those on the upper half of the arch are given first, followed 

 by those on the lower half of the arch as 8 + 13 in the draw- 

 ing. After Schultz and Hanson. Courtesy of the Washington 

 Sportsman. 



Fig. 24. This diagram illustrates 

 the approximate positions of the 

 various tooth-bearing bones in 

 the roof of the mouth of a sal- 

 monoid game fish. After Schultz 

 and Hanson. Courtesy of the 

 Washington Sportsman. 



