NATURAL SCIENCES OF PHILADELPHIA. 279 



gion, and of the sides of the muzzle, these regions being inclosed 

 by membrane only. 



One species, C. semiscutatus., Cope, has the postcoracoid pro- 

 cesses much widened and with a superficial rugose ossification of 

 the derm, thus approaching Brochis. The median portion of the 

 thorax is, however, not inclosed. The sides of the head are also 

 more fully ossified than in other species. 



The typical species present interesting modifications of the in- 

 ferior lips. Thus, that of G. ambiacus is broadly reflexed, of 

 equal thickness, and furnished on its posterior border with two 

 short barbels. In C. trilineatus the lip is recurved, and without 

 barbels, but the margin is thickened into a cord, which is con- 

 nected with the edge of the mandible by a membrane so attenu- 

 ated as to be easily ruptured, when the arrangement resembles 

 closely that seen in Brochis. In the third group the inferior lip 

 appears to be entirely wanting. I add to the characters of the 

 four new species here described those of the three recorded by 

 Giinther, as far as I can learn them. 



Group I. 

 Head longer than high ; barbels to middle of orbit ; "A. 6." 



C. PALEATUS. 



Head higher than long ; barbels to operculum ; A. I. 6. Muzzle long ; 

 dorsal spine moderate serrate; irregularly spotted. C. ambiacus. 



Group II. 



Muzzle short, convex ; barbel to posterior edge of orbit ; dorsal and anal 

 spines shorter, former smooth ; a light lateral band, divided and margined 

 by a black line. C. trilineatus. 



Group III. 



Muzzle produced, acute, concave ; barbel to middle of orbit ; dorsal and anal 

 spines short, former serrate ; no azygus shields ; uniform, with a pale 

 lateral band. C. acutus. 



Muzzle short, acute, concave ; barbels to middle of orbit ; dorsal and anal 

 spines very long, former smooth ; four azygus shields ; olive, black- 

 dotted. C. AMPHIBELUS. 



Group ? ? 



"Head high as long; barbels to gill opening ; A. 8." C. punctatus. 



" Similar to C. paleatns, but fins immaculate ; A. I. 6." C. aeneus. 



"Head higher than long, muzzle short convex; barbels to below eye; 

 dorsal spine long, serrate ; anal short, four or five azygus plates ; anterior 

 scutes with vertical rows of black spots." C. armatus. 



1872.] 



