BLACK-HORSE SUCKER. 815 
Diagnosis.—This species may be known by the small head and long 
dorsal. 
Habits—It is not rare in the Ohio River, but it seldom ascends the 
smaller streams. At the Falls of the Ohio it is frequently but irregularly 
taken, and is sold under the name of Gourd-seed Sucker. Itisalsocalled 
Missouri Sucker and Black Horse. According to Dr. Kirtland, “it 
migrates down the river at the approach of winter. It is esteemed more 
highly for food than any other of the family.” 
Genus 19. CATOSTOMUS. lLeSueur. 
Catostomus, LESUEUR, Journ. Acad. Nat. Sci. Phila., i, 1817, 89. 
Hypentelium, RAFINESQUE, Journ. Acad. Nat. Sci. Phila., i, 1818, 421. 
Decactylus, RAFINESQUF, Ichthyologia Ohiensis, 1820, 
Hylomyzon, AGASsiz, Am. Journ. Sci. Arts, 1855, 205. 
Minomus, GIRARD, Proc. Acad. Nat. Sei. Phila., 1856, 173. 
Acomus, GIRARD, Proe Acad. Nat. Sci. Phila., 1856, 173. 
Type, Cyprinus catostomus, FORSTER = Catostomus longirostrum, LRSUEUR. 
Etymology, kato, low; stoma, mouth. 
Head more or less elongate, its length ranging from three and a half to five in body, 
‘its form varying considerably in the different subgenera; eyes rather small, high up, 
median or more or less posterior in position ; suborbital bones narrow, longer than broad, 
much as in Myxostoma ; fontanelle always present, usually widely open, in two species 
reduced to a narrow slit, but never wholly obliterated ; mouth rather large, always in- 
ferior, and sometimes notably 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 
rogose; pharyngeal bones moderately strong, the teeth shortish, vertically compressed, 
rapidly diminishing in size upwards, the upper surface of the teeth nearly even, or some- 
what cuspidate ; body oblong or elongate, more or less fasiform, subterete, more or less 
compressed ; scales comparatively small, typically much smaller and crowded anteriorly, 
the number in the lateral line ranging from about 50 to 115, the number in a transverse 
series between dorsal and ventrals from 15 to 40; lateral line well developed, straight- 
ish, somewhat decurved anteriorly ; fins variously developed ; dorsal with its first ray 
neatly midway of the body, with from nine to fourteen developed rays; anal fin short 
and high, with probably always seven developed rays; ventrals inserted under the mid- 
dle or posterior part of the dorsal, typically with ten rays, in one subgenus usually nine, 
the number often subject to variation of one; caudal fin usually deeply forked, the 
lobes nearly equal ; sexual peculiarities not much marked, the fins higher in the male 
and the anal somewhat swollen and tuberculate in the spring ; breeding males in some 
species with a rosy or orarge lateral band ; air-bladder with two chambers; vertebra 
in C. teres and C. nigricans 45 to 47. ; 
“*The skeleton in Catostomus is distinguished by the comparative want of solidity, cer- 
bones consisting merely of a network of osseous matter. There is a large and broad fon- 
tanelle on the upper surface of the head, separating the parietal bones, and leading 
