GENUS CYCLEPTUS. 187 



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

 giuous sheath 5 muciferous system not greatly developed ; opercular 

 apparatus not greatly developed, the operculum smooth and narrow. 



thmus moderate; gill-rakers moderately long, soft; pbaryngeal bones 

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



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



'duncle long, the greatest depth contained 4 to 6 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 



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

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



family. . 



Generis Characterizations. 



CYCLEPTUS Rafinesque, 1819. " Cycleptus, (abdominal). Different du genre Catos- 

 >mus. Deux nageoires dorsales, bouche petite, roude, au bout du museau; levres 



irculaires. Famille (Jyprinidia ? C. nigrescens, noiratre ; ventre blauchatre, bouche 

 trousse*e ; queue fourchee. Parvient a deux pieds de long ; ties bon a manger, rare 

 ms 1'Ohio et le Missouri." (RAFIXESQUE, Journ. de Phys. etc. 1819, p. 421.) 

 CYCLEPTUS Rafinesque, 1820. " Difference from the foregoing genus [Catostomus] 



wo dorsal fins, mouth round and terminal." (RAFIXESQUE, Ich. Oh. p. 6.) 



'TIDOSTOMUS Heckel, 1842. " Dentes pectiniformes CO-GO. Pinna dorsalis basi 

 mgata; radio tertio vel quarto longissimo. In reliquis cum genere Catostomo con- 

 .it." (KKCKEL, Fische Syricns, p. 33, or Russeger's Reisen, p. 1023. Species referred to 

 ie genus, Cyprinus catostomus Forster and Catostomus elongatus Le Sueur.) 

 CYCLEPTUS Agassiz, 1655. "As in many other instances, Rafinesque has named, but 

 sither defined nor characterised the geous to which I now call attention. He has not 



