26 CHECK LIST OF THE 



fourth ; pseudobranchiae present. Scales cycloid, large or small. Lateral 

 line decurved, sometimes wanting. Head naked ; fins not scaly. Dorsal 

 fin comparatively long (of ten to fifty rays), without true spine; anal fin 

 short; caudal fin more or less forked; ventrals abdominal, with about ten 

 rays ; pectoral fins placed low, without spine ; no adipose fin ; belly not 

 serrated. Alimentary canal long-. Stomach simple ; no pyloric caeca. Air 

 bladder large, divided into two or three parts by transverse constrictions, 

 not surrounded by a bony capsule. 



Genus ICTIOBUS. (Buffalo Fishes.) 



Body robust ; head very large and strong. Eye moderate, anterior. 

 Fontanelle large, well open. Opercular apparatus largely developed ; the 

 suboperculum broad ; the operculum strongly furrowed. Mouth large for 

 a sucker, terminal, protractile forward, or downward and forward. Man- 

 dible strong, oblique. Lips little developed ; the upper narrow and smooth ; 

 the lower rather full on the sides, but reduced to a narrow rim in front. 

 Jaws without cartilaginous sheath. Muciferous system of head well devel- 

 oped. Isthmus narrow. ' Pharyngeal bones rather weak; the teeth num- 

 erous, moderate or small ; the lower ones gradually larger than the upper 

 ones. Gill rakers long and slender above, becoming shorter downward. 

 Scales large, thick, nearly equal over the body ; lateral line well developed, 

 slightly decurved anteriorly. Dorsal fin elongate; anterior rays somewhat 

 elevated, their length about half that of the base of the fin ; caudal not 

 much forked ; anal fin not much elevated ; pectorals and ventrals moderate. 

 Sexual differences slight. 



This genus contains an uncertain number of species, very few of 

 which have been yet well defined. They are large, coarse suckers, especi- 

 ally characteristic of the streams of the Mississippi Valley, and need much 

 study. 



Subgenus ICTIOBUS. 



(i6) Buffalo-fish. Sucker-mouthed Buffalo. 



(Ictiobus bubalus.) 



Body considerably elevated and compressed above ; the dorsal region 

 subcarinate ; belly thicker ; axis of body above the ventrals, below the 

 lateral line, and nearly twice as far from the back as from the belly. Head 

 moderate, triangular in outline when viewed from the side. Mouth quite 

 small ; mandible about equal to eye. Dorsal fin elevated in front and 

 rapidly declined, the highest ray reaching much beyond the middle of the 

 fin, the seventh ray about half the length of the third or longest. Anal 

 rays rapidly shortened behind ; the middle rays much shorter than the first 

 long ones. Caudal deeply lunate. Colour, pale, slightly dusky ; fins 

 scarcely dusky. D., 29; A., 10; V., 10. Scales, 8, 39, 6. 



