Prosopium quadrilaterale (Richardbon) Frostfish, Pilot 

 Prosopium cylindraceum quadrilaterale (Richardson) 

 Upper jaw reaching below the front of the eye; western states 



Prosopium wiUiamsoni (Girard) Rocky Mountain Whitefish 



62. Anal fin with thirteen to seventeen rays; ascending streams from the Pa' 



cific; breeding males usually with red coloring 63. 



Anal fin with less than thirteen rays 67. 



63. Scale count over 170; tail with oval dark spots in adults 



Oncorhynchus gorbuscha (Walbaum) Humpback Salmon 

 Scale count less than 160; tail with or without spots 64. 



64. With 30 to 40 gill rakers on the first gill arch; color blue above, un- 



spotted 



Oncorhynchus ner\a (Walbaum) Sockeye, Blueback 

 With 20 to 25 gill rakers on the first gill arch 65. 



65. Head depressed, snout produced, with eye about midway in head; with 



or without fine dots, but no definite dark spots 



Oncorhynchus \eta (Walbaum) Dog Salmon 

 Head conical; eye anterior in head; back often spotted 66. 



66. Usually with 15 to 17 rays in the anal fin; back and tail well spotted 



Oncorhynchus tschawytscha (Walbaum) Chinook, King 

 Salmon 

 Usually with 13 or 14 rays in the anal fin; back often spotted, tail usually 

 less so 



Oncorhynchus \isutch (Walbaum) Silver Salmon, Coho 



67. Sides with some red or orange spots (red lost in preserved specimens) ; 



pectoral and pelvic fins with white outer rays or borders (Only the 

 most common species are given here) 68. 



Spots yellowish or dark; with or v/ithout red blotches or a red band 

 along each side; no white outer borders to pectorals and pelvics (Only 

 widely distributed species are included) 71. 



68. Scale count about 120; with inconspicuous white borders to the pectoral 



and pelvic fins; usually with some of the spots cross or star-shaped; an 

 introduced European species 



Salmo trutta Linn. Brown Trout 

 Salmo trutta fario Linn. 

 {Trutta eriox (Linn.) ) 

 Scale count usually over 200; with conspicuous white borders to the 

 pectoral and pelvic fins; dark spots usually not cross or star-shaped; 

 native species Charrs 69. 



69. Back pale-spotted above; western species 



Salvelinus malma spectabilis (Girard) Dolly Varden Trout 

 Back not pale-spotted above; eastern species 70. 



70. Back marbled with dark coloring in adults; maxillary extending well be 



yond the eye; eastern states, and introduced into some western states 



Salvelinus fontinalis (Mitchill) Brook Trout 

 Back not marbled with dark; maxillary extending scarcely beyond the 

 eye; N. H. and Vermont 



Salvelinus aureolus Bean Golden Trout, American Saibling 



266 



