124 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY — IV. 
12§. P. viircsceEis Cope. 
Body elongate, compressed, the caudal peduncle contracted, llead 
short, wide, 5 iii length. Muzzle obtuse, little projectiug. Upper lip 
wide ; lower lip full, emarginate. Jaws with well-developed cartilagi- 
nous sheaths. Scales much reduced iii size forwards. Dorsal rays 10; 
ventral 9; scales 18-103-16. Color olive; lower surface yellow. Head- 
waters of Arkansas Eiver. 
(Cope, Wheelers Expl. W. 100th Mer. v, 07.5, 1876; Jordan, 1. c. 182.) 
61.— CATOSTOITIUS Le Sueur. 
Suckers. 
(Rylomyzon Agassiz ; Acomus and Minointis Girard.) 
(Le Sueur, Joiiru. Acad. Nat. Sci. Phila. i, 89, 1817 : type Cyprinus catostomus Forster = 
Catostomns lonyirostnim Le Sueur.) 
Head more or less elongate, its lengtli ranging from 3?- to 5 times in 
that of the bodyi Eye usually rather small, high up, and median or 
more or less posterior in position. Suborbital bones narrow, longer 
than broad, much as in 2Toxostoma. rontanelle always present, usually 
widely open, in two species reduced to a narrow slit, but never wholly 
obliterated. Mouth rather large, always inferior, and sometimes nota- 
bly so ; the upper lip thick, protractile, papillose ; the lower lip greatly 
developed, with a broad free margin, deeply incised behind, so that it 
forms two lobes, which are often more or less separated. Mandible 
horizontal, short, not one-third the length of the head and not reaching 
to opposite the eye. Lower jaw usually without distinct cartilaginous 
sheath. Opercular apparatus moderately developed, not rugose. Pha- 
lyngeal bones moderately strong, the teeth shortish, vertically com- 
pressed, rapidly diminishing in size upwards, the upper surface of the 
teeth nearly even or somewhat cuspidate. Body oblong or elongate, 
more or less fusiform, subterete, more or less compressed. Scales com- 
jiaratively •small, typic.ally much smaller and crowded anteriorly, the 
numbev in the lateral line ranging from about 50 to 115, the number iu a 
transverse series between dorsal and ventrals from 15 to 40. Lateral line 
well developed, straightish, somewhat decurved anteriorly. Fins vari- 
ously developed. Dorsal with its first ray nearly midway of the body, 
with from 9 to 14 developed rays. Anal fin sliort and high, with probably 
always 7 developed rays. Yentrals inserted under the middle or jmste- 
rior part of the dorsal, typically with 10 rays ; iu one subgenus usually 
9 ; the number often subject to variation of one. Caudal fin usually 
deeply forked, the lobes nearly equal. Sexual peculiarities not much 
