FISHES OF COLORADO 33 



ff. Sides plain or with a single lateral dusky band. 



g. Basal fulcra of the caudal fin not greatly enlarged; caudal peduncle not 

 narrow and elongate. 



h. First (rudimentary) ray of the dorsal fin heavy, blunt and spine-like, 

 broadly joined to the second (i.e., to the first long ray); intestine more 

 than twice the length of the body; mouth terminal; scales large, usually 

 about 45 in the lateral line . . . Pimephales Rafinesque, p. 40 

 hh. First (rudimentary) ray of the dorsal fin not heavy and blunt, usually 

 adnate to the second (i.e., the first long ray). 



i. Inside of the lower jaw with a small hard lump near the tip; scales 

 large, about 35 in the lateral line; intestine more than 3 times as long 

 as the body; peritoneum black; mouth terminal; dorsal fin with its 

 first ray distinctly in front of the origin of the ventrals. 



Hybognathus Agassiz, p. 42 

 ii. Inside of the lower jaw without a hard protuberance; alimentary canal 

 short. 



j. Mouth ventral and sucker-like, the upper Up recurved around the 

 lower at their junction; dorsal fin with first ray distinctly in front 

 of the ventrals; scales rather large, 40-50 in the lateral line. 



Phenacobius Cope, p. 45 

 jj. Mouth not sucker-like, although sometimes rather ventrally placed; 

 base of the first dorsal ray on a level with or posterior to the ventrals. 

 k. Scales in the lateral Une less than 80, usually less than 60. 



1. Colorado species, scales in the lateral line 45-80; if less than 60, 



anal rays 8 Richardsonius Girard, p. 46 



11. Colorado species, scales in the lateral line less than 45 ; if 45-50, 

 anal rays 9 or 10 . . . . Notropis Rafinesque, p. 48 

 kk. Scales in the lateral line more than 80 (Colorado species). 



Ptychocheilus Agassiz, p. 54 



gg. Basal fulcra of the caudal fin much enlarged (see Fig. 36); caudal peduncle 



slender; scales small, 80 or more in the lateral line, often wanting from the 



mid-dorsal and mid-ventral regions . . Gila Baird and Girard, p. 55 



ee. Maxillary barbel present. 



m. Barbel lateral, on the anterior, outer surface of the upper 

 jaw, a little in front of the depression at junction of the 

 two jaws. 



n. Colorado species with a black spot at the base of the 

 first few rays of the dorsal fin; head 3.2 to a little less 

 than 4, usually 3 . 5 in the length. 



Semolilus Rafinesque, p. 57 

 nn. Colorado species with no black spot at the base of the 

 dorsal fin; head 4. 25 to 4.5 in the length. 



Couesius Jordan, p. 59 

 mm. Barbel in the axil at the junction of the upper and lower jaws. 

 O. Scales in the lateral line less than 70; scales with 

 apical radii only; body somewhat compressed; max- 

 illary barbel prominent. 



p. Scales in the lateral line 35-45 ; dorsal, pectoral 

 and anal fins rounded; Colorado species with the 

 first ray of the dorsal on the level with or slightly 

 behind the ventrals. . Hybopsis Agassiz, p. 60 



