CYCLEPTUS 65 



Genus CYCLEPTUS Eafixesque 



Body elongate, little compressed, caudal peduncle very long; head very 

 small, short and slender; mouth small, inferior; hps tuberculate. The 

 skeleton is remarkable for deficiencies of ossification and other features 

 which may indicate affinity with a primitive catostomoid stock. Forward 

 portion of chondrocranium strongly developed, the trabeculse fusing anteriorly 

 into a broad and thick ethmoid plate, which is continuous in front with the 

 bulbular cartilages of the end of the vomer, and above with the broad girdle- 

 like tegmen cranii; bones of skull somewhat heavy, their exposed surfaces 

 more or less rough; prefrontals, meso- and ento-pterygoids very spongy, 

 and other bones subject in varying degrees to incompleteness of ossification; 

 sutures very distinct, never close and strongly joined, with cartilage between 

 the edges of the articulating elements in many instances; configuration of 

 roofing bones of brain case and orbits much as in Ictiobus; nasal foramen 

 closed externally by a sieve-like plate; a small supraorbital bone intervening 

 between lateral wings of prefrontal and frontal; posterior fontanelle repre- 

 sented by a small opening at intercalation of supraoccipital and frontals; 

 anterior fontanelle present, notching ethmoid and extending a short distance 

 backward between frontals; sub- and inter-operculum and branchiostegals 

 rather small; pharyngeal bones narrow and spongy, the teeth from 25 to 35 

 in number, the lower ones somewhat compressed but strong, the remaining 

 teeth weak, diminishing rapidly in size upward; vertebrae 49 in number, rather 

 heavy and poorly sculptured; ribs 13, short and weak; floating pairs 14, very 

 slender and thread-like, their parapophyses (vertebrae 17 to 30) short and 

 stout and similar in form and size, with distal extremities expanded and their 

 free margins crenate; air-bladder in two parts, the posterior very long and 

 slender and much tapered behind, furnished interiorly with a spiral band of 

 supporting cartilage; dorsal rays about 30, the first rays elongated, about half 

 the length of the fin; scales elongate, with a broad membranous posterior 

 border; lateral line complete, a pecuHar and conspicuous membranous area 

 about the posterior terminus of each tube. Mississippi Valley; one species 

 known. 



CYCLEPTUS ELONGATUS (Le Sueur) 

 MISSOURI sucker; black-horse 



Le Sueur, 1817, J. Ac. N.at. Sci. Phila., I, 103 (Catostomus). 



G., VII, 23 (Sclerognathus); J. & G., 121; M. V., 46; J. & E., I, 168; N., 50; J., 64; 

 P., 81; L., 12. 



Body elongate, little compressed and the back httle elevated, depth 

 4 to 5 in length. Size large; length 214 feet. Color dark, bluish black about 

 head; fins dusky to black; spring males almost black, the head covered with 

 small tubercles. Head very small and slender, conic, its length 5.8 to 6.4, 

 width 8.2 to 8.8, depth 8.1 to 8.5 in length of body; snout fleshy, tapering 

 to the bluntly pointed muzzle, which extends considerably beyond the 

 decidedly inferior mouth; distance from eye to muzzle 2 to 2.2 in head; 

 mouth small, its width from 5.8 to 6 in head; hps rather thick, protractile 



