EXTINCT MAMMALIA OF NORTH AMERICA. 403 



ANCHIPPUS. 



Auchippus texanus. 



See page 312, PL XXI, Fig. 13. 



Leidy: Proc. Ac. Nat. Sc. 1868, 231. 

 From the tertiary of Washington Co., Texas. Miocene ? 



ANCHIPPODUS. 



Anchippodus riparins. 



Leidy : Proc. Ac. Nat. Sc. 1868, 232. 



Indicated by a tooth from a tertiary formation, probably miocene, of Shark River, 

 Monmouth Co., New Jersey. 



The tooth, represented in figs. 45, 46, plate XXX, would appear to correspond with 

 a first or second lower true molar of a ruminant, or with any of the series between 

 the first and last molars in Pakeotheriwn or Anchitherium. The crown is much worn, 

 even so as to obliterate some of its distinctive features. It is composed of a pair of 

 demi-conoidal lobes, one before the other, the plane side internally, the convex and 

 sloping side externally. From each lobe descends a fang in the usual manner. No 

 fold, and only a feeble basal tubercle occupies the deep external angular interval be- 

 tween the lobes. The worn triturating surface presents, on the anterior lobe, a wide 

 crescentoid tract of exposed dentine, slightly concave and bordered with thick en- 

 amel. The anterior arm of the crescent is obtuse ; the posterior extends less 

 inwardly and is acute. The posterior lobe exhibits a half ellipsoidal tract of dentine, 

 nearly straight at its inner margin, and bordered with enamel, except behind, where 

 it has all disappeared. The dentinal tracts of the two lobes are connected by a 

 narrow isthmus. The enamel is thick, black and shining, and though it appears to 

 have been originally more or less rough, yet it is now nearly smooth. The measure- 

 ments of the specimen in its present condition are as follow : 



Fore and aft diameter of the crown, ten lines ; breadth of posterior lobe obliquely 

 at base of the enamelled crown, nine and a half lines ; breadth of anterior lobe in 

 same position, eight and a quarter lines; breadth of worn triturating surface of pos- 

 terior lobe, six lines; breadth of do. on anterior lobe, five and a half lines. 



RODENTIA. 

 LEPORWuE. 



LEPUS. 



Lepus sylvaticus. 



Leidy : Trans. Am. Phil. Soc. 1857, XI, 18 ; Holmes' Post-pliocene Fossils of South Carolina, 



1860, 113 ; Hall and Whitney's Rep. Geol. Sur. Wise, and Whitney's do. Up. Missis. Lead 

 Region, 1862, 424. 



