56 UNIVERSITY OF COLORADO STUDIES 



Gila robusta Baird and Girard 

 Round Tail, Bony Tail, "Gila Trout" (Figs. 34, 35 and 36) 



Gila robusla Baird and Girard, Proc. Acad. Nat. Set. Phila., p. 368, 1853 (Zuni River); 

 Jordan and Evermann, BM. 47, U.S. Nat. Mus., p. 227, 1896 (Uncompahgre River at Delta). 



aia elegans Baird and Girard— Jordan, Bull. U.S. Fish Cam., Vol. IX, p. 27, 1889 (Gunnison 

 at Delta). 



Gila pandora Cope — Cope and Yarrow, Wheeler Survey, Vol. V, p. 66i, 1875 (Pagosa). 



Gila egregia Cope — Cope and Yarrow, Wheeler Survey, Vol. V, p. 662, 1875 (Loma, Grand 

 River, wrongly ascribed to the Rio Grande). 



Body elongate, somewhat compressed, depth 4.6 (yotmg) to almost 6, usually 

 about 5 in the length to the base of the caudal fin; dorsal and ventral profiles 

 sloping regtilarly in small specimens, dorsal profile just back of the head rising 

 abruptly, so that the body in this region bears a more or less distinct hump; 

 head rather large, somewhat flattened dorsally, especially in old individuals, 3 . 5 

 (young) to 4.7 in the length; eye large, situated nearer to the tip of the snout 

 than to the posterior margin of the operculum, its diameter 5 or 6 in the head, 

 about 2 in the interorbital distance, 2 or a little less in the snout; nostril large, 

 septum very prominent and much elevated, its length about 2 in the eye; mouth 

 terminal, broad, and slightly oblique, angle of the mouth reaching the level of the 

 anterior margm of the eye; premaxillaries protractile; dorsal fin short, length 

 of its base less than that of the first ray, base of the first ray almost equidistant 

 from the tip of the snout and the base of the caudal, rays usually 10, sometimes 9; 

 tip of pectorals not reaching the ventrals; ventrals reaching or passing the anal 

 opening; anal fin with 9 or 10 rays; caudal peduncle elongate and quite narrow, 

 its least depth 1.25 to 1.5 in the maxillary, equalling or slightly exceeding the 

 diameter of the eye; basal fulcra of the caudal fin much developed; caudal fin 

 long and broad, deeply forked, its width equalling or exceeding the greatest depth 

 of the body; scales small, irregularly placed, ventral parts and mid-dorsal region 

 often incompletely scaled or naked; lateral line very prominent, strongly decurved 

 and rather irregular, pores beginning at the base of the occipital region and extend- 

 ing well out onto the base of the caudal fin; scales about 30 in vertical series 

 between the base of the first ray of the dorsal and the base of the ventrals, 85 to 

 9S in the lateral line. 



General color sUvery, dusky dorsally; axils of the pectorals and ventrals and 

 the base of the anal fin yellowish to orange; males with more or less red on the 

 sides of the head. Size small to moderately large, average specimens about 9 

 inches in length, very large individuals 12 to 15 inches. 



The Round Tail has very little economic importance since its body is so bony 

 as to make its value as a food fish slight. The flesh of large specimens is occa- 

 sionally eaten and is said to have a very good flavor. While collecting at Grand 

 Junction the writer found this species confused with the young and smaU speci- 

 mens of Ptychocheilus lucius Girard by the local fishermen, both species being 

 known as "Squawfish." 



