Cope.] 480 (June 7, 
II. Anterior rays shorter, measuring the anterior half or a little more 
of the base of the dorsal ; (muzzle conic or projecting). 
D. XXIV. A. VII. Depth 2% in length; head 4.3 in same; back 
much elevated, anterior dorsal rays measure to the 15th ray. 
' C. GRAYI. 
D. XXVIII, V. X. A. VII. Depth 2.5 in length; head 4.25 in same; 
scales 8-5 ; short, stout ; long dorsal rays measure to 22 ray. 
C. THOMPSONI. 
D. XXVI-VII, V. X. Depth 8 times in length, head 3.5 times; muz- 
zle elongate conic; eye median, large; anterior D. rays not thickened, 
nearly as long as base of fin. . ; C. BISON. 
D. XXVII to XXX; A. VIII; scales 6-5 ; oblong, long dorsals to 22 ray 
in adults ; depth 2.7 in length, eye small anterior. C. CYPRINUS. 
D. XXX A. VII; anterior dorsal rays thickened, osseous, short, reach- 
ing 16th ray ; head small, .4.5 to5 times in length ; eye small anterior ; 
fusiform, depth 3 times in length. Cc. NUMMIFER. 
In the number of the radii of the ventral and anal fins, the species are 
not always entirely constant; thus in one C. bison there are VI, in 
another VII anals. In C. cyprinus some have [X and others X ventrals. 
In young examples of the species just named, the long anterior dorsal 
rays are longer than in the adult, but not so much so as to be confounded 
with the long rayed species of section one. The margins of the scales in 
this genus and Bubalichthys are serrate, their structure thicker than in 
the Ptychostomi. 
Gill has adopted the genera of the Catostomi as left by Agassiz, while 
Ginther rejects most of them. Moxostoma, Ptychostomus and Catosto- 
mus I regard as distinct genera of the typical form, to which I add Pla- 
copharynx. Of those with finer and more numerous pharyngeal teeth, 
Cycleptus is distinct in its completely ossified cranium, as I have pointed 
out in an essay on the Cyprinide of Pennsylvania. Bubalichthys is well 
characterized by the form of its pharyngeal bones, as shown by Agassiz. 
The remaining Rafinesquian genera Carpiodes and Ichthiobus, are but 
doubtfully distinct from one another. Carpiodes is the older name, with 
which Selerognathus, Cuv., Val., may be associated as a synonyme. 
Carpiodes difformis, Cope. 
Spec. nov. 
This species has a remarkably obtuse muzzle, which with the large eye, 
almost gives it the appearaace presented by monstrous perch and carp 
where the premaxillary bones are atrophied. Viewing the top of the 
head from a position opposite a point mid-way between the dorsal fin and 
end of the muzzle, the spine of the premaxillary bone is not visible. In 
the C. selene these spines are very distinctly prominent, in the (0. cutisan- 
serinus slightly so. 
The dorsal outline of this fish is arched, elevated to the anterior dorsal 
radii, and then regularly descending. The long dorsal rays extended, 
reach to beyond the origin of the caudal. Lateral line nearly straight, 
