226 



U. S. P. R. E. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



4. CATOSTOMUS SUCKLII, Grd. 

 PLATE LI. 



SPEC. CHAR. Head constituting the fifth of the entire length. Eye small. Mouth rather sall ; lips moderately developed, 

 covered with conspicuous* papillae. Isthmus of medium width Dorsal fin as high as long ; its anterior margin somewhat nearer 

 the insertion of the caudal fin than the extremity of the snout. Insertion of ventrals a little in advance of the middle of the 

 dorsal, and equi-distant between the extremity of the snout and the fork of the caudal. Posterior extremity of anal extending 

 beyond the rudimentary rays of the caudal. Greyish olive above ; yellowish olive beneath. 



SYK. Catostomus sucklii, GRD. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 175. 



The head forms the fifth of the entire length. It is sub-quadrangular, the upper surface 

 rather sloping towards the blunt snout. The eye is small and sub-elliptical ; its horizontal 

 diameter being contained somewhat over five times in the length of the side of the head. The 

 anterior margin of the dorsal fin is equi-distant between the tip of the snout and the insertion 

 of the caudal. Its height is equal to its length, and its upper margin is slightly concave. The 

 posterior margin of the caudal is deeply emarginated, crescent-shaped. The insertion of the 

 ventrals is situated somewhat in advance of the middle of the dorsal fin. 

 I) 2, 12 ; A 2, 8 ; C 5, 1, 8, 8, 1, 4 ; V 10 ; P 18. 



The scales are large and but a little smaller anteriorly than posteriorly ; they are sub- 

 elliptical in shape, longer than deep, with their anterior and posterior margins irregular, 

 exhibiting radiating grooves upon the anterior and posterior sections. The upper regions are 

 greyish olive, and the inferior regions yellowish olive. The young being of a darker and less 

 yellowish tint. 



^References to the figures. Plate LI, fig. 1, represents the adult Catostomus sucklii, size of 

 life. Fig. 2 is a scale from the dorsal region. Fig. 3, a scale from the lateral line. Fig. 4, 

 a scale from the abdominal region. Fig. 5 is the young of the same species. 



List of specimens. 



TRIBE OF CHONDROSTOMI 



The characters of Chondrostomi, as derived chiefly from the American representatives, consist 

 in the absence of barbels ; in the position of the mouth, which is generally overhung by the 

 upper jaw, and sometimes both jaws are equal. The pharyngeal teeth are of the grinding 

 type (Denies masticatorii) and cultriform kind (Denies cultriformes ), disposed upon a single 

 series, with one exception only, and that occurs occasionally in Campostoma. I say occasionally, 

 because in the majority of cases there is also but one single row in the latter genus. Exoglossum 

 is removed from this group, of which it has none of the characters, except the absence of 

 barbels. 



SYN. Chondrostomi, AGASS. in Amer. Journ. of Sc. 2d series, XIX, 1855, 94. GRD. in Proc Acad. Nat. Sc. Philad. VIII, 

 1H56, 175. 



