GENUS CYCLEPTUS. " 187 



what as in Catostomus, but less full, incised behind; jaws without carti- 

 laginous sheath; muciferous system not greatly- developed ; opercular 

 apparatus not greatly developed, the operculum smooth and narrow. 

 Isthmus moderate; gill-rakers moderately long, soft; pharyngeal bones 

 strong, the teeth stout, increasing in size downwards, rather wide apart. 



Body elongate, moderately compressed, not much elevated, the caudal 

 peduncle long, the greatest depth contained 4 to G times in length. 



Scales moderate, about equal over the body, not closely imbricated, 

 with wide exposed surfaces, the number in the lateral line from 55 to 

 GO, and about 17 in a transverse series from dorsal to ventrals; edges 

 of scales serrate; lateral line well developed, nearly straight. 



Fins rather large ; dorsal fin beginning in front of ventrals and ending 

 just before anal, of about 30 rays, strongly falcate in front, the first and 

 second developed rays in length more than half the length of the base 

 of the fin, the rays rapidly shortened to about the eighth, the length of 

 the remaining rays being nearly uniform and all short ; caudal fin large, 

 widely forked, the lobes about equal; anal fin quite small, low, of 7 or 

 8 developed rays, scaly at base; ventrals moderate, with 10 rays; pec- 

 torals elongate, somewhat falcate. 



Sexual peculiarities somewhat marked; the males in spring with black 

 pigment ; the head then covered with small tubercles. 



Air-bladder with two chambers, the anterior short, the posterior 

 elongate. 



But a single species of this singular genus is as yet known. It is 

 found in the waters of the Mississippi Valley, and, although not a rare 

 fish, it is by no means as generally abundant as are many others of its 

 family. 



Generic Characterizations. 



Cycleptus Eafinesque, 1819.—" Cycleptus, (abdominal). Different dii genre Catos- 

 tomus. Denx nageoires dorsales, bouebe petite, roude, au bout du museau; levres 

 circulaires. Famille ('yprinidia ? C. nigrescens, noiratre ; ventre blaucbatre, bouebe 

 retroussde ; queue fourch^e. Parvient a deux pieds de long; ti^s bon a manger, rare 

 dans rOhio et le Missouri." — (Kafinesque, Journ. de Phijs. etc. 1819, p. 421.) 



Cycleptus Eafiuescxue, 1820.—" Difference from tbe foregoing genus ICatostomiis'i — 

 two dorsal fins, mouth round and terminal." — (Rafixesque, Ich. Oh. ]). 6.) 



Rhytidostomus Heckel, 1842. — " Dentes pectiniformes 60-60, Pinna dorsalis basi 

 elongata; radio tertio vel quarto longissirao. In reliquis cum genere Catostomo con- 

 gruit." — (Heckel, Fische Syriens, p. 33, or Russeger^a Eeisen, p. 1023. — Species referred to 

 the genus, Cyprinus caiostomus Forster and Catostovms elongatus Le Sueur.) 



Cyclkptus Agassiz, 1855. — "As in many other instances, Rafinesque has named, but 

 neither defined nor characterised the genus to ■which I now call attention. He has not 



