CATOSTOMID.E. XXV. 43 



without the characters of the rudimentary subopercle and maxil- 

 lary, and the absence of scales, which distinguish the Cat-fishes. 

 The chief families are the Cyprinidce and the Characinidce ; the 

 latter, abundant in South America, have an adipose fin and usually 

 teeth in the jaws, (cv, well; evros, within ; yvaBos, jaw.) 



FAMILY XXV. CATOSTOMID-^3. (THE SUCKERS.) 



Body oblong, covered with cycloid scales ; head naked ; jaws 

 toothless and without barbels, the maxillary forming a large part 

 of the edge of the upper jaw ; mouth usually protractile, the lips 

 generally thick and fleshy ; lower pharyngeal bones falciform, with 

 many comb-like teeth in one row ; branchiostegals 3 ; gill mem- 

 branes united to isthmus ; dorsal fin rather long, of 11 to 50 rays, 1 

 without spine ; anal short ; caudal forked ; ventrals abdominal, of 

 about 10 rays ; pectorals low ; no adipose fin. Alimentary canal 

 long, without coeca. Air-bladder large, divided into two or three 

 parts by transverse constrictions. Genera 11, species about 60, 

 inhabiting the rivers of North America ; two species in Asia. 

 The Suckers feed on plants and small amimals ; the flesh is rather 

 tasteless and full of small bones. They ascend the rivers to spawn 

 in spring, at which time the males have usually the A. and C., and 

 often other parts of the body, covered with tubercles. 



a. Dorsal fin elongate, its rays 25 to 50 in number; air-bladder in two parts. 

 b. Fontanelle present; body oblong-ovate. (Jctiobince.) 



c. Dorsal rays 25 to 35; scales large (34 to 41) . . . . ICTIOBUS, 41. 

 bb. Fontanelle obliterated by the union of the parietal bones ; body elon- 

 gate. ( Cycleptince.) 



d. Mouth small, inferior, with thick papillose lips; scales small (56). 



CYCLEPTUS, 42. 

 aa. Dorsal fin short, its rays 10 to 18. (Catostomince.) 



e. Air-bladder in two parts; lower pharyngeals slender, with small teeth. 

 f. Lips thick, papillose; lateral line complete and continuous; scales 



small (55 to 115) ; fontanelle present; mouth small, inferior. 



CATOSTOMUS, 43. 

 ff. Lips thin, plicate; scales large (40 to 50). 



g. Lateral line wholly wanting, at all ages. . . . ERIMYZON, 44. 

 gg. Lateral line imperfect in young, nearly complete in the adult. 



MlNYTREMA, 45. 



ee. Air-bladder in three parts; fontanelle present; scales large (about 



45) ; lateral line complete. 

 h. Mouth normal, the upper jaw protractile; the lips more or less 



plicate. 



t. Lower pharyngeal bones moderate, the teeth compressed, gradu- 

 ally increasing in size downward MOXOSTOMA, 46. 



ii. Lower pharyngeal bones very strong, with the lower teeth much 

 enlarged, subcylindrical and truncate; the upper teeth small 

 and compressed PLACOPHARYNX, 47. 



1 In this family, the rudimentary rays before dorsal and anal are not counted. 



