2 2 Bulletin American Museum of Natural History. [Vol. XIV, 



Palaeosinopa veterrima, n. g. et sp. 



Palaosinopa veterrima " Wortman," MATTHEW, Bull. Amer. Mus. Nat. 

 Hist., iSgq, p. 31. Name only. 



Stypolophus whitice Osborn & WoRTMAN, '92, p. no, not 5. whiticE Cope. 



Generic characters : Dentition ^'^"^ ? . Metastyle moderately extended on 



m^, rudimentary on m^-. Trigonid of three subequal cusps ; heel larger than 

 trigonid, hy^ and en^ strong, hl^ present on all molars, strong only on mg. The 

 worn state of the upper molars in the type specimen precludes exact compari- 

 son with Didelphodus , to which the genus is most closely allied. 



Specific characters: 

 Upper incisors ra- 

 ther large, roots not 

 compressed, the third 

 placed behind and 

 within the second, 

 leaving a deep notch 

 for the lower canine 

 between i- and c-. 

 Canines rather small, 

 first upper premolar 

 one - rooted, second 

 two-rooted, third 

 two-rooted, but with 

 the posterior root the 

 wider, crown with robust protocone and rudimentary postero-internal heel ; 

 fourth three-rooted with well-separated internal cusp. First and second molars 

 with rudimentary hypocone or postero-internal cingulum, third molar transverse 

 apparently large. First lower premolar one-rooted, others two-rooted, trenchant, 

 with small heels and minute anterior basal cusps. 



Type No. 95, upper and lower jaws, teeth badly worn. Associated type. No. 

 150a, a lower jaw with unworn teeth. Referred specimens Nos. 2849, 2851, 

 2852. All from the Lower Eocene Wasatch Beds of the Big Horn Valley, 

 Wyoming. 



Measurements of Type Specimen. 



Fig. 8. Palffosinopa veterrima Matthew. A, upper jaw, from 

 below, type specimen. No. 95 ; B, external view of lower jaw, co- 

 type, No. 150a. Both natural size, from the Wasatch Beds, Big 

 Horn Basin, Wyoming. Amer. Mus. Exp. 1891. 



