64 



GREGORY: XOTIIARCTUS, AN AMERICAN EOCENE PRIMATE 



The axillary border, so far as preserved, was not sharply inflected so as to form two sharp ridges 

 with a flat intervening fossa for the tendon of the teres minor, as is the case in Cebus, Alouatta, and Hapale. 

 In Nolharctus, on the other hand, the merest beginning of this inflection may be indicated in the form 

 of a low swelling on the subscapular surface; there is also a slight swelling of the outer surface of the 

 border, indicating the lower end of the strip for the teres minor. Quite similar details were observed in 

 Propithecus coquerelli. Accordingly it can be stated that, at least at the lower end, there was no sharp 

 medially directed ridge on the subscapular surface of the scapula, as there is in Cebus, Alouatta, and 

 Hapale: and that here again the nearest observed resemblances are found in a specimen of Lemur varius 

 and in Propithecus. 



The subscapular surface, so far as preserved, is perhaps nearest to that of Propithecus. That part 

 of the surface which was immediately beneath the lower end of the spine is indicated by a gentle concavity 

 flanked posteriorly by a low roimd eminence, much as in Lemur, Lepilernur, and Propithecus. In Cebus, 

 Alondtla, and Hapale, on the other hand, the subscapular surface presents a widely different appearance 

 due partly to the presence of the shar]3 medial crest on the axillary border already noted. 



So far as indicated by the specimen, the lower end of the jire- and postspinous f()ssa> were also lenun-i- 

 form in tyjie. 



Cla\icle 

 Platr XXI II 



The medial half of the left cla^'icle is preser\'ed in the type of A\ oshorni (Amer. Mus. No-. 11474). 

 It is very similar to that of Lemur vumqoz but has a stouter, less compressed shaft and a less expanded 

 facet for the sternum. In the Lemuridte and Indrisida? the clavicle is but gently curved; in all the Platyr- 

 rhini and Catarrhini examined it is more or less 8-sha]ied and is capable of more \'aried movements, as in 

 l)rachiation. 



Humerus 



Plates XXVII.. XXVIII; Text Fi-s. ft, 7, S 



This element is represented l)y l>oth humeri of N. oshorni, No. 11474, and by several other humeri 

 belonging to allied species. An extended comparison of the humerus of Nolharctus shows that it has 

 the following primiti^'e mammalian characters in contrast with the specialized primate characters of 

 anthropoid apes and man: 





Xotliarctu.s 



Arithmjioiil 



1 pes' find Man 



1. 



Shaft, Relative Length 



Short 



Very long 





2 



Delto-pectoral Crest 



Prominent 



Reduced 





3. 



Head 



Of moderate size 



Large and spheric; 



il 



4. 



Inclination anti Direction of Head 



Chiefly toward the hack of the shaft 



Largely toward tl 

 shaft 



e inner side of the 





( 'ontour of Bone in Side ^'iew 



Gently S-shaped 



Straight 





(i. 



Sn]:)inator Crest 



Very prominent, extending well up the 

 shaft to a point opposite the lower 

 end of the delto-pectora! ridge 



Reduced, ending 1 



clow middle of shaft 





iMitepicondylar Foramen 



Present, very large 



Absent 





S. 



( 'ai)itelhnn 



Ball-like in center, produced externally 



Truncate extern; 



lly, sh;u-ply .liffer- 







toward ^"ery inconspicuous external 



enti;ited from 



proniinent c\tcrn;d 







epicondyle 



ejjicondx Ic 





