136 



greCxOry: notharctus, an American eocene primate 



was but faintly foreshadowed in p'*; it is connected with the protoconid by a small oblique crest forming 

 the short posterior limb of the potential anterior V or summit of the trigonid, of which the crista anterior 

 and paraconid form the anterior limb; the potential trigonid, as in most primitive insectivorous types, 

 projects far above the level of the low potential talonid; its posterior wall, culminating above in the 



Fig. 40. Diagram: occlusal relations of left upper and lower cheek teeth in Notharctus. Compare Fig. 38. 



A. Notharctus oshorni. Amer. Mas. No. 11466. X i'. C. Notharctus crassus. Amer. Mus. No. 11982. X v. 



B. Notharctus crassm. Amer. Mus. No. 11982. X f. D. Notharctus venticolus. Amer. Mus. No. 14655. X t- 



proto-metaconid ridge, descends steeply to the talonid; it shears past the crista anterior and flat antero- 

 hngual face of the paracone of p^. The basin of the talonid is represented by a fossa in the postero- 

 lingual half of the talonid; this fossa is separated from a smaller fossa, situated on the labial side of the 

 talonid and representing the central external valley, by a sharp crest which represents the lower end 

 of the primitive crista posterior and will give rise in later types to the crista obUqua or anterior limb 

 of the posterior A of the tooth. The hypoconid is represented by a low median cusp at the junction of 



