ANALYSIS OF GENERA. 103 



List of N^ominal Species of Catostomidce, icith Identifications — Continued. 



ANALYSIS OP GENERA OF CATOSTOMID^. 



" Dorsal tin sbort, subquadrato, with ten to eighteen developed rays: body oblong or 



elongate: gill-rakers feeble. {Catostomincc.) 



a. MoutU siugnlar, the upper lip not protractile, greatly enlarged, the lower lip 



developed as two separate lobes : operculum veiy short : air-bladder 



in three parts: scales large : fontanelle well developed: lateral line 



present: pharyngeal bones and teeth ordinary Quassilahia, 1. 



uti. Mouth normal, the lower lip entire or merely lobed, either tubercular or plicate. 



b. Air-bladder in three jKirts : lateral line continuous: fontanelle present : scales 



large, subequal. 



c. Pharyngeal bones very strong, with the lower teeth much enlarged, subcy- 



lindrical and truncate, the teeth of the upper part of the bene small 



and compressed: mouth large, somewhat oblique, with very thick 



lips Placophakynx, 2. 



cc. Pharyngeal boues moderate, the teeth compressed, gradually larger down- 

 wards: mouth moderate or small, the lii)s usually plicate. 



Myxos'ioma, 3. 

 bb. Air-bladder in two parts. 



d. Lateral liue interrupted or wanting : scales large (40 to r>0 lu the course of 



the lateral Iilc) : lips plicate. 



e. Lateral lino incomplete, obsolete in the young, becoming developed in the 



ivdult, but always more or less interrupted: mouth small, inferior. 



Minyti;kma, 4. 



ee. Lateral liue entirely wanting : mouth somewhat oblique.. Ekimyzox, 5. 



dd. Lateral line complete and continuous : scales small, o.5 to 115 in the course 



of the lateral line. 



/. Fontanelle present. 



g. Mouth verj' large, terminal, ()bli([ue : lips thin, nearly smooth. 



Chasmistes, 6. 



gg. Mouth inferior, moderate or small, with thick, papillose lips. 



Catosto.mus, 7. 



ff. Fontanelle obliterated by the union of the parietal bones: mouth small, 



inferior, with thick, ])apillose lips, the lower jaw provided with a 



cartilaginous sheath . . .> Pantosteus, 8. 



