ANALYSIS OF GENERA. 103 



Lint of Nominal Species of Catostomidce, with Identifications Continued. 



ANALYSIS OF GENERA OF CATOSTOMID.fi. 



Dorsal fin short, subquadrate, with ten to eighteen developed rays: body oblong or 

 elongate: gill-rakers feeble. (Catostominoe.) 



a. Moutb singular, the upper lip not protractile, greatly enlarged, the lower lip 

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

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

 present: pharyngeal bones and teeth ordinary QUASSILABIA, 1. 



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

 b. Air-bladder in three parts: 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 bone small 

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



lips PLACOPHARY^X, 2. 



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

 wards: mouth moderate or small, the lips usually plicate. 



MYXOSTOMA, 3. 

 bb. Air-bladder in two parts. 



d. Lateral liue interrupted or wanting : scales large (40 to 50 in the course of 



the lateral hue) : lips plicate. 



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

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



MlNYTREMA, 4. 



ee. Lateral line entirely wanting : mouth somewhat oblique.. ERIMYZON, 5. 

 dd. Lateral line complete and continuous : scales small, 5.5 to 115 in the course 



of the lateral line. 

 /. Fontanelle present. 



g. Mouth very large, terminal, oblique : lips thin, nearly smooth. 



CHASMISTES, 6. 

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



CATOSTOMUS, 7. 



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

 inferior, with thick, papillose lips, the lower jaw provided with a 

 cartilaginous sheath PAXTOSTEUS, 8. 



