GEOLOGICAL SUEVEY OF THE TERRITOEIES. 549 



JJfOTHARCTUS LONGICAUDUS, Cope. ^ 



Pantolestes longicaudus, Cope. Proceed. Amer. Philos. Soc, 1872, ]). 467, (August 3.) 



This form is one of those mixed types which are so abundant in the 

 Bridger Group. Its dental formula is M. 3, P. M. 4, c. 1, incisors un- 

 known. The molars in the only specimen known are so worn as to pre- 

 clude exact description. They evidentlv possessed anterior and posterior 

 lobes, separated by a valley, which was most expanded on the inner side. 

 The last molar exhibits a short heel posteriorly, which probably sup- 

 ported a small tubercle. The three premolars are all two-rooted and 

 compressed in form. The last presents a crown composed of one large 

 anterior compressed cusp, and a much lower posterior one. There is a 

 slight cingulum in front. The canine is lost, but its alveolus indicates 

 that it was a stout tooth. 



So far as the known dental structure goes, this species resembles nearly 

 the Notharctus of Leidy, but possesses a more carnassial fourth premolar. 



Themandibular ramus is quite slender, and there is a large foramen 

 below the first true molar. The masseteric fossa is pronounced. 



I originally assigned bat 3 P. M. to this species, but now find that it 

 possesses four, thus resembling Notliarctus. It differs from all the 

 species described by 3Iarsh, in having the second premolar two-rooted, 

 and from Leidy's two species in its slender proportions. 



The remains of this species were found together by the writer in the 

 Bridger beds on Black's Fork, Wyoming. 



ANAPTOMOEPHUS, Cope. 



Proceedings of the American Philosophical Society, 1872, p. 554, published by the 



author October 12. 



This genus is represented by the left ramus mandibuli of a single 

 species. The posterior jDortion is broken away, and the teeth remaining 

 perfect are the P. M. 2, and M. 1 and 2. The ramus, though small, is 

 stout, and deeper at the symphysis than at the last molar. What ap- 

 pears to be the dental foramen is nearly opposite the bases of the crowns 

 of the molars. The mental foramen issues beneath the first premolar. 



Dentition of the ramus mandibuli, In. 2, 0. 1, P. M. 2, M. 3, total, 16. 

 It differs from monkeys in some respects; there is no interruption in the 

 series near the canine, and the symphysis, though massive, is not coos- 

 sified. Further details are, the last molar is three-lobed and elongated 

 behind. The composition of the crowns of the preceding molars consists 

 of four opposed lobes, which are very stout, and connected transverse!}'" 

 by a thin ridge behind, or in close contact in front. The premolar tooth 

 which is best preserved, is a perfect second, which, while having two 

 roots, possesses a crown which stands almost entirely on the anterior, 

 presenting a curved sectorial crest forward and upward. 



The dentition is more typically quadrumanous in this genus than in 

 the last, and it might be referred decidedly to Lemuridce were it not for 

 the unossified symphysis. It no doubt represents a distinct group or 

 family from Tomithermm, and one more nearly related to the existing 

 types of Madagascar and South Africa. 



Anaptomoephus jsmulus. Cope, loc. cit. 



This species was about as large as a marmoset or a red squirrel. The 

 enamel of the teeth is entirely smooth. 



