224 



NORTH-CAROLINA GEOLOGICAL SURVEY. 



FIGS. 45 & 46 



From the teeth of Mososaurus those of Pliogonodon differ 

 in their narrower proportion, their straightness, their circular 

 transverse section, their relatively narrower planes, and in 

 their possession of plicae. From the teeth of Polyptychodon 

 they differ in the possession of dissimilar planes and carinae, 

 and in their less degree of robustness ; and from those of 

 Pleiosaurus in the existence of divisional planes and the cir- 

 cular section. 



PREPANODON IMPAR. LEIDY. (FigS. 45 & 46.*) 



This genus and species are proposed on the crown of a 

 tooth resembling the corresponding portion of the inferior 



canine of a bear, except that it has 

 but a single carina, and that on the 

 concave border internally. The spe- 

 cimen was discovered by Prof. Em- 

 mons, at Elizabethtown, Cape Fear, 

 North-Carolina. It is black in color, 

 curved, conical, most convex exter- 

 nally, and is oval in transverse section. The base is hollowed 

 conically, and the enamel is smooth. The length of the spe- 

 cimen is three-quarters of an inch ; the antero posterior di- 

 ameter of its base is seven lines, and its transverse diameter 

 five lines. 



The tooth I suspect to have belonged to a crocodilian rep- 

 tile, though it may possibly even prove to be a mammalian 

 relic. 



* Described by Prof. Leidy. 



