FISHES OF COLORADO 71 



Superorder PHYSOSTOMI 



Air bladder connected with the ahmentary canal by a ductus pneumaticus; 

 no Weberian apparatus. 



Order Isospondyli' 



Herring, Salmon, the Smelts and Related Deep-Sea Forms 



Maxillaries and premaxillaries distinct; barbels wanting; shoulder girdle 

 connected with the skull by the postemporal bone. 



This order is represented in Colorado by the Grayling, Trout and Whitefish, 

 all of which are game fishes. 



Family THYMALLIDAE 

 The Graylings 



Dorsal fin high and long, of 19 to 24 rays; adipose fin present; general form 

 trout-like; parietal bones meeting mesially; frontal bones not reaching the supra- 

 occipital bone. 



This family includes five species all referable to the genus Thymallus, found 

 in the cold clear waters of northern America and the Arctic regions. As food 

 fishes and from the standpoint of the fisherman the Graylings are among the best 

 of the fresh-water fishes. In both general appearance and habits the Graylings 

 are much like the Trout, but the high dorsal fin and the striking colors of the 

 former are quite distinctive. The name Thymallus is derived from a Greek word 

 referring to the odor of thyme which is supposed to be quite evident when the 

 Grayling is first taken from the water, a belief which Izaak Walton credited, for 

 he wrote of the Grayling, "and some think he feeds on water thyme for he smells 

 of it when first taken from the water." It seems, however, that sportsmen do not 

 agree in this matter, for Henshall^ says of the Grayling that "however it may 

 have been in days of old, it is not so now, though an odor of cucumbers is some- 

 times perceptible when it is first out of the water." 



Genus THYMALLUS Cuvier 

 The Graylings 

 Thymallus Cuvier, Regne Animal, ed. II, Vol. II, p. 306, 1829. 



Body somewhat compressed; head short; teeth on the premaxillaries, maxil- 

 laries and lower jaw; air bladder very large; scales small, about 90 in the lateral 

 line; species brightly colored, dorsal fin with orange, red or purplish spots; caudal 

 fin distinctly forked; represented in Colorado by a single introduced species. 



» Since the Isospondylous fishes found in Colorado, both native and introduced forms, have been planted 

 in as many streams of the state as possible, the Colorado specimens examined are not listed, unless for particu- 

 lar reasons, as they do not contribute to the understanding of the natural distribution of these species. 



' Bass, Pike, Perch and Others, p. 175, 1903, New York. 



