152 



GREGORY: NOTHARCTUS, AN AMERICAN EOCENE PRIMATE 



posterointernal roots having somewhat similar relations to the potential talonids and trigonids of ps, p2. 

 (Plate XLII, fig. 10.) 



In Adapts parisiensis (StehUn, 1912, figs, on pp. 1180, 1181) the last deciduous lower molar (dp4) 

 was fully molariform, but more compressed than nii. Comparison of the crown with that of Nothardus 

 is not possible. (Fig. 47.) 



Succession of the Teeth 



Stehlin (1912, pp. 1183-1188) has shown that in Adapts the probable order of replacement after the 

 eruption of the deciduous teeth was as follows. 



1. Mt and pi appear. 



2. M? appear. 



3. Mi appear. Replacement of deciduous incisors by permanent incisors (ii being somewhat 



ahead of i|). Deciduous canines drop out and permanent canines begin to come in. 



4. Replacement of dpf, dpi by p|, p|. 



5. Replacement of dpii by pi. Canines assume final position; earlier in females than in males. 



Fig. 48. Skull of Notharctns crassu-s. Reconstruction based on Ainer. Mus. No. 12567. Middle Eocene (Upper 

 Bridger), Wyoming. Natural size. 



Fig. 49. SkuW oi Nothardus osborni. Type, Amer. Mus. No. 11466. Middle Eocene (Lower Bridger), Wyoming. 

 Lacrymal region restored from other specimens. Natural size. 



The evidence is incomplete in the case of Nothardus, especially with regard to the incisors and canines, ' 

 but so far as it goes it indicates that the order of replacement was not dissimilar to that of Adapts. From 

 two of the specimens above noted (Amer. Mus. Nos. 13029, 12578) it is established that the third lower 



