GENUS CYCLEPTUS. 187 



what as iu Catostomus, but less full, iuciscd behind ; jaws without carti- 

 laginous sheath; muciferous sj'stem not greatly dGveloi)ecl ; oj)eicular 

 apparatus not greatly developed, the operculum smooth and narrow. 

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

 strong, the teeth stout, increasing iu size downwards, rather wide ai)art. 



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

 peduncle long, the greatest dei)th contained 4 to G times in length. 



Scales moderate, about equal over the body, uot closelj' imbricated, 

 with wide exposed surfaces, the number in the lateral line from 5o to 

 CO, 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 flu beginning iu irout of ventrals and ending 

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

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

 of the flu, 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 flu 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 i^osterior 

 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. 



Genet-is Characterisations. 



Cycleptus Rafinesque, 1819.—" Cj^cleptus, (abdomiual). Different du genre Ciitos- 

 tomns. Deux nageoires dorsales, boncbe petite, ronde, an bout du museau ; Icvres 

 circuhiires. Famille (Jyprinidia ? C. nigrescens, iioirixtre ; ventre blancbatro, bouche 

 retroussdo ; queue fourchee. Parvient a deux pieds de loug ; tits bou a manger, rare 

 dans rOhio et lo Missouri." — (RAriXESQUK, Journ. de Fhys. etc. 1819, p. 421.) 



Cvci.KrTUS Rafinesque, 1820. — " Difference irom the foregoing genus \_Catostomv.s'\ — 

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



RilYTiDOSTOMUS Hccl^el, 1842.—" Dentes pectiniformes GO-GO. Pinna dorsalis basi 

 elongata; radio tertio vel quarto longissimo. In reliquis cum genere Catostonio con- 

 gruit." — (Hkckkl, Fische Syricns, p. 33, or Russcger'a Edsen, p. 1023. — Species referred to 

 the genus, Cyprinu8 catostomua Forster and Catostomus elongatus Le Sueur.) 



Cycleptus Agassiz, 185.'). — "As in manj- other instances, Rafinesque has named, but 

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



