310 FISHES. 



c. Pharyngeal bones very broad and strong ; the lower 

 7 to 10 teeth on each side, greatly enlarged and trun- 

 cate; the teeth on the upper part of the bone small, 

 as usual in the family. . . Placopharynx, 2. 



cc. Pharyngeal ijones not especially enlarged; the teeth 

 strongly compressed, of the usual t3^pe. 



Myxostoma, 3. 

 J)h. Air bhidder in two parts. 



d. No lateral line Erimyzon, 5. 



dd. Lateral line imperfect. . . JMinytrema, 4. 

 ddd. Lateral line well developed ; lips tuberculate. 

 e. Fontanelle distinct ; no maudibulary sheath. 



/. Scales moderate, not crowded forwards, about 

 equal over the body ; body long and little com- 

 pressed; head transversely concave between 

 orbits, long and flattened ; the physiognomy 

 being therefore peculiar ; ventral rays 9. 



Hypextelium, 6. 



ff. Scales small, smaller anteriorly and much 

 crowded; head transversely convex between 

 orbits ; ventral rays normally 10. 



Catostomus, 7. 



* Body much elongated, sub-cylindrical forwards ; dorsal elongate, 

 falciform, of 30 or more rays; fontanelle obliterated by the 

 union of the parietal bones. {CycleptuicB.) 



g. ]Mouth small, subinferior, with papillose lips ; scales rather 

 small Cycleptus, 8. 



*** Body oblong oval, compressed ; dorsal elongate, elevated in 

 front, of 20 or more rays; fontanelle present. {Buha- 

 UcJithyince.) 

 h. Dorsal rays about 30 in numljer (24 to 33) ; anal vays about 

 10 (9 to 12); scales large. 

 i. Pharyngeal bones narrow, with the teeth relatively thin and 

 weak, 

 j. Mouth small, inferior, protractile downwards ; dorsal fin 

 often greatly elevated. . . . Carpiodes, 9, 



