PLIOGONODON. IO3 



naturally terminated in a truncated manner ; the enamel forming an abrupt ring 



surrounding a shallow deijression of the dentine. The specimen to the extreme 



edge of the broken base is everywhere invested with thin, 



shining, and nearly smooth enamel, being only marked by No. 35. 



feeble longitudinal striation and stronger transverse ridges of 



growth. 



In shape the tooth is conical, strongly compressed from with- 

 out inwardly, and has its broad surfaces defined before and 

 behind by finely denticulated trenchant borders. In transverse section it forms a 

 long ellipse with very acute poles, as seen in the outline. No. 35. 



The length of the specimen in its present condition is two inches ; the breadth 

 just below the middle, where it is unbroken, is thirteen lines ; and the thickness in 

 the same position is seven lines. 



Whether the tooth belongs to the same Eeptile as some of the bones described 

 in the preceding pages can only be conjectured, and under the circumstances I have 

 indicated it under the name heading the present chapter. It may belong to Disco- 

 saurus or CimoUasaurus, but the question can be determined only after further 

 discovery. 



PLIOGOiVODOIV. 



Pliogonodon prisctis. 



Pliogonodon priscus, Leibt, Proceedings Academy Natural Sciences, Philadelphia, 1856, 255. 

 Pliogonodon nobilis, Leidy, Emmons, Report North Carolina Geological Survey, 1858, p. 223, figs. 43, 44.' 



Under the above name I described the mutilated crowns of two teeth submitted 

 to my inspection by Prof. Emmons, who obtained them from a Miocene deposit of 

 Cape Fear, North Carolina. The specimens are, nevertheless, suspected originally 

 to have belonged to the Green-sand formation. Their character I have not ascer- 

 tained, and though I suspect them to have an affinity to Mosasaurus, they may be 

 CrocodiUan. 



The specimens are elongated conical, in transverse section circular. One of them 

 is straight, the other feebly curved. They are provided internally with acute ridges 

 or carinas, defining the inner and outer surfaces of the crown, which is subdivided 

 into numerous narrow planes diversified with a few vertical interrupted plicae 

 more numerous on the inner surface. The base of the crovvTi is hoUowed ; the 

 dentine is fissured in concentric lamiuae, and the enamel is minutely vnrinkled. 

 When perfect the crowns measured about two inches in length, and three-fourths 

 of an inch in diameter at base. 



* The change of name I cannot account for except through inadvertence. 



