Gregory: notjiarctus, an American eocene primate 



83 



distal end shows a small facet Avhich may have lodged the sesamoid to which is attached the tendon of 

 the adductor pollicis muscle, which is very strong in lemurs. The metacarpals are shorter and stouter 

 than those of either Lemur or Cebus, this betokening powerful muscles of the palm. The metacarpal 

 which is identified as number II is a third shorter than metacarpal III, whereas in Lemur, metacai-pal 

 II is only a httle shorter than metacarpal III, and in Cehus it is nearly equal to it. This disparity in 

 length between II and III is further emphasized in the modern Chiromys and is very probably a primi- 

 tive character. The short metacarpals are retained in Lepilemur, although here they are thinner than 

 those of Notharctus. 



In conclusion, it seems hardly necessary to give a fuller and more detailed description of each indi- 

 vidual known element of the manus of Notharctus. It msiy suffice to state that the writer has made care- 

 ful comparisons of every such element with the homologous elements of representative Lemuridse and 

 Cebidse; and that with regard to the detailed conformation of each element, Notharctus, with few excep- 

 tions, is nearer to Lemur than to Cebus. 



Comparative Measurements 











Lepilemur 



Lemur 



Lemur 









N. lyramnis 



mustelinus 



inongoz 



varius 









No. 11478 



No. .31251 



No. 31254 





Metaearpiil I 



Lcn.uth 







S . 5 





1().4 



I, Breadth 



.[■ Distal Knd 





3.3 



4.3 



5 . 7 



11 



Lfii-th 





13..-) 



10. 



IS.O 



2().4 



II 



Bmulth 



.f Distal End 



4.(i 



3.2 



3 . (i 





III 



Lcn-th 





120 . 



1 1 . 



19. () 





ill 



Breadth 



)f Distal End 





3.4 



4. 





IV 



I,(-n«-th 





IS. 



14.3 



19. () 



27.3 



IV 



Breadth 



.F Dista! End 



.) . 7 



3.4 



4.5 



5 . 5 





Lenj;th 





14.3 



12. 



17.3 







Breadtli 



)f Distal End 



4. 3 



3. 



4.5 





I'roxinial Pliala 



n\ of Difi'it T 







11. 



lfi.5 







II 





10. 



14.3 



24.3 







III 



25 . 5 e.st. 



12.5 



17.3 



27 5 







IV 



27.3 



15.5 



IS. 5 



2S. 







\' 





12.5 



15. 



24. 



Pelvic Limb 

 Pelvis 



Plates XXXII, XXXIII; Text Fig.s. 12, 13, 14 



The pelvis of Notharctus is preserved in Nos. 11474, 11478 and 11479. It is essentially of lemurine 

 type, differing chiefly in the shorter, wider ilia, and relatively longer ischia. It differs in many particulars 

 from the pelvis of New World monkeys. Old World monkeys, apes, and man; it is in each case more 

 primitive — that is, very close to the tupaioid or Menotyphla type. 



1. As viewed from below, the opposite halves of the pelvis of Notharctus form a sort of lyre, the 

 blades of the iha diverging anteroexternally beyond the first sacral vertebra. In all lemurs this feature 

 is still more pronounced. In the New World monkeys, on the other hand, in the ventral view the oppo- 

 site ilia are more parallel to each other and do not diverge anteriorly, but their ventral surfaces are spread 



