263 



to the last, as seen in Fig. 13. In tlie largest and oldest specimens, tiie in- 

 termediate three teeth are nearly equal in size, as seen in Figs. 16, 17. In 

 the specimens of intermediate size and age we notice some irregularity, hut 

 generally a disposition to increasing uniformity of size in the corresponding 

 teeth. 



The first tooth is directed backward toward those behind; the otliers are 

 parallel in their direction inwardly. 



The crown of the terminal teeth is more mammillary than in the interme- 

 diate ones, in which it is oval with the longer diameter directed from above 

 downward, and the short diameter fore and aft. The masticating surface of the 

 teeth is broad, oval, moderately convex, sometimes nearly flat, and usually 

 slightly depressed at the middle or at the center. The crowns resemble 

 strikingly those of worn human premolars, and are covered by tliick, smooth 

 ^nameloid substance. 



The teeth are supported on strong bony columns as long as the crowns 

 They project from the lower ramus of the pharyngeal below tlie position of 

 the upper or postei'ior ramus. The last of the series projects backward and 

 inward from the conjunction of the two branches, as usual in cyprinoids. 



In the older specimens, it would appear that the first tooth of the series 

 was after a certain time not replaced. 



Most of the specimens present evidences of the existence of two minute 

 teeth forming a secontl row above the principal one. 



The pharyngeal bones, in accordance with the strong crushing teeth they 

 sustain, are stronger than usual in the ordinary living carp-like fishes. 



The pharyngeal bone is widest opposite the larger teeth. The oblique 

 surface directed forward and outward exhibits the usual deep hollows extend- 

 ing to the bases of the teeth, or through the bone in some cases when the 

 latter are absent or shed. The posterior and inferior surfaces are flat, and 

 transversely striated, or, in the older ones, more or less strongly ridged. The 

 anterior border is vertically concave. The external border, acute below and 

 obtuse behind, is unusually thick. The inner border, extending backward 

 beyond the conjunction of the two branches of the bone, is that wliich sus- 

 tains the teeth. 



The upper or posterior ranuis is- comparatively short, bent forward and 

 inward, and ends in a p(jint by which it was suspended from tlie occiput. 

 The extremity of (he louiT or anterior ramus, extending in advance of the 



