212 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY III. 



outer iiiaigi!). The peduncle of the symphysis is imuh longer propor- 

 tionally, and more pointed than in Carpioden and BubuUchthys. Tiie 

 teeth are very numerous, small, thin and comi)ressed in Carpiofles, but 

 the lower ones are gradually larger tlian the upper ones. Their inner 

 edge is slanting outwards, and not uniformly arehed as in Bubniiclithys, 

 or truncate as in Cycleptus, the innermost margin rising somewhat in the 

 shape of a projecting cusp. Gill-rakers of anterior arch long and slender 

 above, becoming shorter downwards. 



Body heavy, robust, not especially arched above nor greatly com- 

 pressed, the form somewhat elliptical, the depth 2^ to 3^ in the length 

 of the body. 



Scales large, thick, nearly equal over the bodj', their posterior edges 

 somewhat serrate, the lateral line well developed, but not as distinct as 

 iu Curpkxlcs, slightly decurved anteriorly, the number of scales in its 

 coursi' .}() to 42; 13 to 1"> in a transverse series from dorsal to ventrals. 



Dorsal lin with an elongate basis, its number of rays 25 to 31), the 

 anterior rays somewhat elevated, their length about half that of the 

 base of the fin; caudal not much forked; anal fin not much elevated, 

 its rays about in number; pectorals and ventrals moderate, th" latter 

 with about 10 rays. 



Sexual peculiarities, if any, unknown. Coloration dark, not silvery, 

 above dusky olive; lower tins more or less black. 



Air-bladder with two chambers. 



Size very large. 



The claim of this group to generic rank has been questioned by Pro- 

 fessor Cope and others. The difl'erences in the pharyngeal teeth are 

 perhaps hardly sufficient to distinguish it from Carpiodes, but at present 

 I am inclinetl to think that the great development of the inandilile, 

 which forms a large and terminal month, ain[)ly snnicient for generic 

 distinctii^n. The relations of the group to Bubalichlhys are doubtless, 

 in reality, closer. lehthj/obufi bears much the same relatioii»to Buba- 

 lichtliyn that Clinstmstcs does to Catostomus, and, so far as the month is 

 concerned, but iu a greater degree, that Erinn/zon bears to Mini/trcma 

 ■ and Placophanjnx to Mif.rnstnmn. The head of Ichthi/obus is much larger 

 and stouter, and the whole body more robust ami less compressed than 

 \u Carpiodes. I know iVoni autopsy but a single species of Ichthyobua. 

 It has, however, been described uiuier several different names. So far 

 as is known, the genus is confined to the valley of Ihe Mississipj)!, no 

 species having been recordeil from the Great Lakes, or from any streams 



