90 



GREGORY: NOTHARCTUS, AN AMERICAN EOCENE PRIMATE 



this condition is connected with the fact that the animal can reach further forward and upward with the 

 hind hmb than was the case in Notharctus, which is again more primitive than the modern type. 



The great trochanter is much less expanded than that of Lemur and lies below the level of the head, 

 whereas in Le)frur it projects widely above it. When the femur is articulated with the pelvis and com- 

 pared with those of Lemur it is seen that in Notharchis the space for the deep gluteal muscles was more 

 restricted and that these muscles were shorter, while their locus of insertion, the great trochanter, was 

 smaller. Hence, in all probability, Noiharetuf; could not leap so far in proportion to its body weight as 

 the modern Lemur varius can. 



1 2 - 3 



Fii;-. ( "oniparative series: v\ght iemora oi N()fkarrfi(}t, Adajjis, Lemur. Back view. Natural size. 



1. Notharctus osborni. Amer. Mus. No. 11474. 



2. " Adapis parisiensis." After Filhol. 



3. Lemur mongoz. Amer. Mus. No. 22886. 



The external tip of the lesser trochanter is more slender and acute than that of Lemur; this proba- 

 bly implies that the ilio-psoas muscle was less powerful than it is in Lemur, just as the leaping power 

 of Notharctus was supposedly somewhat less. The third trochanter is similar to that of Lemur, but 

 smaller and less protuberant; hardly different enough, however, to indicate any marked difference in the 

 gluteus maximus and fjuadratus femoris muscles which were attached to this process on the outer and 



