62 UNIVERSITY OF COLORADO STUDIES 



Horny-heads are very hardy and make excellent bait for the large game fishes, 

 being recommended by many as the best live bait. This Chub spawns in the 

 late spring. 



Colorado specimens. — University Museum: St. Vrain Creek, Longmont, October 17, 1903 

 (2 specimens, 85 and 115 mm.), C. Juday and D. W. Spangler, No. 16; Boulder Creek, Boulder, 

 April 23, 1904 (90 mm.), J. Henderson, No. 36; Colorado State Historical and Natural History 

 Museum: Clear Creek, August 15, 1900 (2 specimens, 105 mm.), W. C. Ferril; State Teachers' 

 College Museum: Cache la Poudre near Greeley, A. E. Beardsley. 



Genus PLATYGOBIO Gill 

 The Flat-headed Chubs 



Platygobio Gill, Trans. Amer. Phil. Sac. Phila., Vol. V, p. 178, 1863. 



Moderately large carnivorous Cyprinids; body rather elongate and com- 

 pressed; head short; alimentary canal short; mouth large, terminal or slightly 

 oblique; maxillary barbel present and prominent, inserted at the junction of the 

 upper and lower jaws; dorsal fin inserted on a level with or usually in front of 

 the ventrals; scales large; lateral line complete and quite straight; size small 

 to medium, length up to 12 inches. The two species of this genus are found in 

 the western portion of the Mississippi Valley, one species ranging as far north 

 as Saskatchewan. A single species is here listed from Colorado, this in the 

 Arkansas River. The record of Cope,' under the name Pogonichthys communis 

 Girard from Pueblo, is placed under Platygobio physignathus (Cope), as subsequent 

 collections from the Arkansas, at Pueblo and above, have yielded only that 

 species of Platygobio. Pogonichtkys communis Girard was described from the 

 upper Missouri and is considered a synonym of Platygobio gracilis (Richardson). 

 If it should be shown by more extended collections that two species of Platygobio 

 are found in the Arkansas at Pueblo, Cope's record would have to be transferred 

 to P. gracilis (Richardson). Since there is a possibility that these two species 

 do occur together in the Arkansas, or that P. gracilis occurs in the Platte drainage, 

 as it is a species of the upper Missouri, the following key for their separation is 

 given: 



a. Dorsal, pectoral and ventral fins deeply falcate; length of the free portion at the tip of the 



dorsal 2 or 3 times the diameter of the eye in length ... P. gracilis (Richardson) 



aa. Dorsal, pectoral and ventral fins slightly falcate; length of the free portion at the tip of the 



dorsal about equal to the diameter of the eye in length. . . . P. physignathus (Cope) 



Platygobio physignathus (Cope) 

 Thick-jawed Chub (Fig. 30) 



Ceratichthys physignathus Cope — Cope and Yarrow, Wheeler Survey, Vol. V, p. 651, 1875 

 (Arkansas River, Pueblo). 



Platygobio physignathus (Cope) — Jordan, Bull. U.S. Fish Com., Vol. IX, p. 17, 1889 (Fountain 

 Creek, Pueblo; Arkansas River, Canyon City); Jordan and Evermann, Bull. 47, U.S. Nat. Mus., 

 p. 326, 1896 (Arkansas River, Pueblo). 



■ Wliecler Survey, Vol. V, p. 653, 1875. 



