BIG-JAWED SUCKER. 831 
Diagnosis —This species may be known by the presence of about 17 
dorsal spines and a large mouth. 
Habits.—This is a large species frequently taken with M. macrolepido- 
tum in Lake Erie. I have also seen several from the Ohio River at Cin- 
cinnati and Marietta. It is a species of northern distribution. 
GENUS 23. PLACOPHARYNX. Cope. 
Placopharynx, COPE, Proc. Am. Philos. Soc. Phila., 1870, 477. 
Type, Placopharynx carinatus, Cope. 
Etymology, plax, a broad surface; pharugx, pharynx. 
This genus is identical with Myxostoma in a\l respects, except in the development of 
the pharyngeal bones and teeth. The pharyngeal bones are very strong and the teeth 
on the lower half of the bone are much reduced in number (6 to 10). They are nearly 
cylindrical in form, being little compressed, and with a broad, rounded or flattened 
grinding surface. In+ize and form, these enlarged teeth are extremely irregular. The 
upper teeth are small, and compressed as in Myxostoma. The mouth in Placopharynx is 
larger than in any species of Myxostoma and the lips are much more developed. 
But one species is known. | 
48. PLACOPHARYNX CARINATUS Cope. 
Big-jawed Sucker. 
Placopharynx carinatus, CoPpE, Proc. Am. Philos Soe. Phila., 1876, 467.—JORDAN, Fishes 
of Ind., 1875, 221 (name only); Man. Vert , 1876, 296; 2d Ed., 1&78, 311; Proe. Acad. 
Nat. Sci. Phila., 1¢77,72; Bull. U.S. Nat. Mus., ix, 1677, 50 (name only); xii, 1878, 
108; Ball. U.S Geol. Sarv., vol. iv, 1877, No. 2, p. 417.—NrELson, Buil. No. 1, Ills. 
Mus. Nat. Hist., 1876, 49.—JoRDAN and COPELAND, Check List, 1876, 158.—JorDan 
and GILBERT, in Klippart’s Rept., 1¢77, 53 (name only).—KLIPPART, First Report of 
Ohio Fish Commission, 1877, 86. 
Description —Body oblong, moderately compressed, heavy at the shoulders; head very 
large ; eye small, behind the middle of the head ; mouth extremely large, the lower jaw 
oblique when the mouth is closed, the mouth thus opening forward as well as down- 
ward ; lips very thick, coarsely plicate, the lower lip foll and heavy, truncated behind ; 
head above evenly rounded (carinate, according to Professor Cope) ; color brassy-green 
above, pale below; lower fins red; head 33; depth 3%; D. 13; scales 6-45-65; V. 9, 
Length 18 to 24 inches. 
Habitat, Mississippi Valley and Upper Great Lakes. 
Diagnosis. —This large coarse species may be certainly known only by 
the examination of its pharyngeal teeth. 
Habits—This fish is probably common in the Western Rivers, but owing 
to its great similarity of form to the Common Red Horse, has been over- 
looked by most naturalists. The writer has met with the following 
specimens: (a) acomplete skeleton of a very large specimen found by Dr. 
J. M. Wheaton in the Scioto River near Columbus; (6) two young speci- 
