104 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY III. 



'* Dorsal fin elongate, more or less elevated in front, of about 25 or more developed 

 rays : air bladder in two parts. 

 tFontanelJe obliterated by the union of the parietal bones: head short and small : 

 body elongate. {Cycleptince.) 

 h. Mouth small, inferior, with very thick, papillose lips : scales small, .% to 60 in 



the course of the lateral line Cyci.eptus, 9. 



ttFontanelle well developed : head large : body oblong or ovate : scales large, 35 to 

 45 in the course of the lateral line. {Bubalichthyince.) 

 i. Dorsal rays in moderate number (24 to 33). 

 j. Mouth comparatively small, inferior, protractile downwards. 



k. Pharyngeal bones narrow, with the teeth comparatively thin and weak. 



Carpiodes, 10. 

 kk. Pharyngeal bones strong, the teeth comparatively coarse and large, in- 

 creasing in size downwards Bubalichthys, 11- 



jj. Mouth quite large, terminal, protractile forwards : pharyngeal bones and 



teeth moderate : lips thin, nearly smooth Ichthyobus, 12. 



it. Dorsal fin very long, of about 50 developed rays Myxocyprinus, 13 



Genus QUASSILABIA Jordan £ Bray ton. 



Lagochila Jordan & Brayton, Pioc. Ac. Nat. Sc. Phila. 280. 1877. (Preoccupied in 



conchology as Lagochilus.) 

 Quassilabia (J ORiiATs; & Braytox) Jordan, Man. Vert. E. U. S. ed. 2d, 401, 1878. 



Type, LagocMla lacera Jordan & Brayton. 



Etymology, quassiis, broken or torn; lahia, lip. 



Suckers like Myxostoma in every respect excepting the structure of 

 the mouth and opercula. Head shortish, conical, with lengthened snout; 

 its length 4J to 5 times in that of the body, the opercular region being 

 reduced, so that the eye is well backwards: suborbital bones narrow : fon- 

 tanelle large, widely open. Mouth large, singuhir in structure, inferior, 

 the upper lip not i:)ro tractile, greatly prolonged, closely [)licate. Lower 

 lip much reduced, divided into two distinct elongate lobes, which are 

 weakly papillose. The split between these lobes extends backwards to 

 the edge of the deutary bones, which are provided with a rather hard, 

 horny plate, as in Pantosteiis. The lower lip is entirely separated from 

 the upper at the angles by a deei) fissure. The skin of the cheeks 

 forms a sort of cloak over this fissure, the crease separating this skin 

 from the mouth extending up on the sides of the muzzle. The crease 

 between the lips extends down on the under side of the head. System 

 ot muciferous tubes well developed. 



Pharyngeal bones not dissimilar from the usual type in Myxostoma^ 

 rather weak, with numerous small teeth. 



Body elongate, not much compressed, not elevated. Fins moderate, 

 of precisely the type usual in Myxostoma. 



