Living Fishes 123 



neath there is a yellowish or orange color about the bases of the 

 fins. 



Three native species come from the Pacific slope, representing 

 as many genera not found elsewhere in Colorado. Only one of 

 these (Agosia yarrowi of Jordan and Evermann) is small and 

 more or less minnow-like, the length not exceeding five inches. 

 The fish quite closely resembles Rhinichthys, and could be mis- 

 taken for it. The scales have radii all around; in Rhinichthys 

 cataractae dulcis I found about 12 apical radii and five distinct 

 basal ones. Next in size is Gila robusta of Baird and Girard, 

 called Round Tail, varying from nine to 15 inches in length, and 

 having a strongly forked tail, curiously swollen at the base. 

 According to Ellis, the form described from Utah as G. seminuda 

 of Cope and Yarrow is a subspecies of G. robusta, distinguished 

 by having no scales on the mid-ventral portion of the body as 

 far back as the base of the ventrals, and no scales on the mid- 

 dorsal region as far back as the middle or last ray of the dorsal 

 fin. The original specimen appears to have been immature, but 

 a fish about nine and one-half inches long, obtained by E. R. 

 Warren and J. W. Frey in the Bear River at Lily, Routt County, 

 appeared to me to be this G. seminuda. The scales are elongate, 

 with parallel or even concave sides, the laterobasal corners 

 prominent though rounded, the basal lobe very large. A new 

 study of Gila should be made by some one able to obtain a large 

 amount of material. The third cyprinid of the western slope is 

 the so-called White Salmon (Ptychocheilus lucius of Girard), 

 which reaches a length of five feet and a weight of nearly a hundred 

 pounds. It occurs in the Grand, White and Yampa rivers and 

 their tributaries. The caudal fin is deeply forked, and the back 

 is dusky greenish. The young have a distinct caudal spot, and 

 a dusky lateral stripe. There is no abrupt swelling of the base 

 of the tail-fin. 



An interesting fish is the Flat-headed Chub, Platygobio phy- 

 signathus of Cope. It is found in the Arkansas River from 

 Salida to Pueblo, and in Grape Creek, which runs into the 

 Arkansas. As the generic name suggests, it has a somewhat 

 flattened head; a matter of considerable interest because in the 

 Himalayas this sort of modification has reached a much more 

 advanced stage in the genus Homaloptera, in which the head and 



