500 Bulletin 47, United States National Museum. 



upper border of the pectoral dusky ; a vague dusky blotch on the upper 

 middle rays of the anal; ventrals entirely plain. Length of type 16 

 inches. Kainloops Lake, Okanogan Lake, Kootenay Lake, and other 

 lakes tributary to Fraser River or to the Upper Columbia ; locally 

 abundant; a fine large trout, slender and graceful, somewhat different in 

 appearance from the ordinary a Steelhead," but not distinguished by any 

 technical character of any importance, and doubtless intergrading fully 

 with the latter. 



Salmo Icamloops, JORDAN, Proc. U. S. Nat. Mus., 1892, Kamloops Lake, British Columbia. 

 (Type, No. 44238. Coll. A. 0. Bassett.) 



781. SALMO IRIDEUS, Gibbons. 

 (RAINBOW TROUT; COAST RANGE TROUT.) 



Head 4 ; depth 3 ; eye 5. D. 11 ; A. 10 ; scales 21-135-20, varying con- 

 siderably. Body comparatively short and deep, compressed, much more 

 elongate in males than in females. Head short, convex, obtusely ridged 

 above. Mouth smaller than in other species, the rather broad maxillary 

 scarcely reaching beyond eye, except in old males. Eye larger than in 

 other species. Vomerine teeth in two irregular series. Dorsal fin mod- 

 erate; caudal fin distinctly, though not strongly forked. Color bluish 

 above, the sides silvery; usually everywhere above profusely but irreg- 

 ularly spotted, the spots extending on the sides and on the vertical fins; 

 spots on caudal small ; belly nearly plain ; sea-run specimens nearly plain 

 silvery; with red lateral band and blotches. Weight i to 6 pounds. 

 Mountain streams of the Pacific Coast ; the typical form found in the 

 brooks of the Coast Range in California, from the Klamath River to the 

 San Luis Rey. Abundant and variable, probably entering the sea, and 

 perhaps growing larger there, becoming a " Salmon Trout." 



This form differs from Salmo gairdneri chiefly in the larger scales. Other 

 characters are its small size and brighter colors; both sexes with a red 

 lateral band. It is subject to large local variations, some of these land- 

 locked in peculiar brooks, (e. g., Purisima Creek in San Mateo County, 

 California, where the individuals are small and brightly colored, popu- 

 larly regarded as distinct species). Its range extends from the coast of 

 Washington southward to San Diego County, California (Rio San Luis 

 Rey). It is thought by some anglers that the young fishes hatched in 

 the brooks from spawn of gairdneri remain in mountain streams for 

 from six months to three years, going down to the sea with the high 

 waters of spring, after which they return to spawn as typical gairdneri. 

 Those which are landlocked or do not descend remain irideus all their 

 lives. As against this view we have the fact that to the northward irideus 

 and gairdneri are always distinguishable and the scales in gairdneri are 

 always smaller than in typical rainbow trout, (irideus, lainbow-like.) 



Salmo irideus, GIBBONS, Proc. Cal. Ac. Nat. Sci., 1855, 36, San Leandro Creek, Alameda 



County, California; JORDAN & GILBERT, Synopsis, 312, in part, 1883. 

 Salmo rivularis, AYRES, Proc. Cal. Ac. Nat. Sci., 1855, 43, Martinez, California. 



