Jordan and Evermann. Fishes of North America. 497 



Represented in the Upper Arkansas and South Platte rivers by 

 779i. SALMO MTKISS STOMIAS (Cope). 



(GllEE.N-BA.tK TllOUT.) 



Mouth small; scales small, about 180. A small black-spotted trout, 

 rarely reaching a pound in weight, close to var. mykiss, differing mainly 

 in the very large size of its black spots, which are mainly gathered on the 

 posterior half of the body. Back deep green, sides sometimes red. Flesh 

 deep red. Head waters of Arkansas and South Platte rivers, in brooks 

 and shallow places in lakes ; abundant, (oro/taaf, big-mouthed.) 



Salmo slomias, COPE, Haydeu's Geol. Surv. Wyom. for 1870 (1871), 433, South Platte River, 



locality unknown. (Coll. Dr. Hammond.) 

 Salmo mykiss stomias, JORDAN, Bull. U. S. Fish. Conim., ix, 1889, 15, pi. 1, fig. 2. 



Represented in the lakes in eastern Colorado by 



779j. SALMO MTKISS MACDONALDI, Jordan & Evermann. 



(YELLOW-FIN TROUT.) 



Head 4 j depth 4| to 5 ; eye 5| ; snout 4. D. 12 ; A. 11 ; B. 10 ; scales 

 40-184-37, 125 pores. Head long, compressed, the snout moderately 

 pointed; mouth rather large, the maxillary If to 2 in head; hyoid teeth 

 present; opercle long, 4i in head, its margin strongly convex. Allied to 

 subspecies pleuriticus, but with the head and opercles longer and the color 

 different. Body elongated , compressed. Gill rakers 10 -}- 10. Scales small, 

 regularly placed. Color light olive ; a broad shade of lemon-yellow along 

 sides ; lower fins bright yellow ; no red anywhere except the " cut-throat" 

 dash characteristic of Salmo mykiss. Body posteriorly, and dorsal and 

 caudal fin profusely speckled with small pepper-like dots, smaller than 

 the nostril; on head and anterior parts fewer none of these spots are 

 present. Flesh pale. A very handsome trout, abundant on gravelly bot- 

 toms in Twin Lakes,* tributary to the Arkansas River in the Saguache 

 Range near Leadville, Colorado ; not found in brooks. It reaches a 

 weight of nearly 9 pounds. It is probably descended from the form 

 called pleuriticus, certainly not from its associate stomias, with which it has 

 very little in common. (Named for Col. Marshall McDonald, United States 

 Fish Commissioner.) 



Salmo mykiss macdonaldi, JORDAN & EVERMANN, Proc. U. S. Nat. Mus., 1889 (January 20, 1890), 

 453, Twin Lakes, Colorado ; (Type, No. 41730. Coll. Geo. R. Fisher); JORDAN, Bull. 

 U. S. Fish Comm., ix, 1889, 11, pi. 1, fig. 1. 



780. SALMO GAIRDNERI, Richardson. 

 (STEELHEAD; HARDHEAD; "SALMON TROUT.") 



We retain the name Salmo gairdneri for the large sea trout of the 

 Pacific Coast and their derivatives ; forms typically with moderate or 

 small scales, and without the strongly-marked red dashes at the throat 



*This form of trout occurs in company with subspecies stomias, but in Twin Lakes, the two 

 are entirely distinct, the habits, size, and coloration being notably different. If we were to con- 

 sider the Arkansas Basin alone, the two must be ranked as distinct species, but these and all 

 other American trout seem to be connected by intergradations. Apparently macdonaldi is derived 

 from the Colorado River pleuriticus, which may be descended from xpiluniB, the latter in turn from 

 stomias. Stomias, viryinalis, henshawi, and bouvieri seem to have sprung directly from mykiss. 



F. N. A. 33 



