GENUS CARPIODES. 191 



the fleshy portion of the cheek below ; fontanelle always present, well 

 developed. 



Mouth always small, horizontal and inferior, the mandible less than 

 one-third the length of the head, the lips thin, the upper protractile, 

 narrow, the lower quite narrow, ^-shaped, or rather fj-shaped, behind; 

 both lips feebly plicate or nearly smooth, the plicae often more or less 

 broken up ; jaws without cartilaginous sheath ; muciferous system 

 moderately developed ; opercular apparatus well developed, the sub- 

 opercle broad, the operculum in the adult more or less rugose 5 isthmus 

 moderate ; pharyngeal bones remarkably thin and laterally compressed, 

 with a shallow furrow along the anterior margin on the inside, and another 

 more central one on the outline of the enlarged surfaces ; teeth very 

 small, compressed, nearly equally thin along the whole inner edge of 

 the bone, forming a fine comb-like crest of minute serratures; their 

 cutting edge rises above the inner margin into a prominent point. 

 Gill rakers of anterior arch slender and stiff above, becoming reduced 

 downwards. 



Body ovate or oblong, the dorsal outline more or less arched, the 

 ventral outline more nearly straight, the depth from half to one-third 

 the length, the sides compressed; the back notably so, forming a sort of 

 carina ; caudal peduncle short and deep; scales large, about equal over 

 the body, their posterior margins slightly serrate; lateral line well 

 developed, nearly straight, with 34 to 41 scales, 12 to 15 scales in a 

 cross-row from dorsal to veutrals ; dorsal fin beginning near the middle 

 of the body, somewhat in advance of ventrals, falcate, its anterior rays 

 very much elevated and usually filamentous, their height ranging from 

 J to 1J the length of the base of the fin, the number of developed rays 

 ranging from 23 to 30; caudal fin well forked, the lobes equal ; anal fin 

 comparatively long and low, emarginate (in males?), its number of 

 developed rays usually 8; ventrals shortish, with usually 10 rays ; pec- 

 torals short. 



Sexual peculiarities little marked ; in some species, at least, the males 

 in spring have the snout minutely tuberculate. 



Coloration always plain; pale olivaceous above, white below, but 

 hardly silvery, the fins all partaking of the color of the region to which 

 they belong. 



Air-bladder with two chambers. 



Size medium or rather large. 



This genus was first recognized and defined by Professor Agassiz in 



