GREGORY: NOTHARCTUS, AN AMERICAN EOCENE PRIMATE 77 



Relation of the Humeral Index to Habits 





oREADTH 



IjENGTH 



Indfx 



iSeiiiiiossoruu iypos 









Dd.Sj/jlllS 



26 



60 



23 



Onjcicroiiiis 



()7 



155 



23 



Tdxulcd 



3-1: 



90 



26 



bolcnoaon 



19 



45 



24 



Ambulcitory to Ciirsoruil lypcs 









Olo'uodoti 



44 



143 



32 







io/ 



oU 





20 



CO 



00 



44 



I roc you 



WW 



109 



50 



Cynwlurus 



34 . 5 



17S 



51 



Primitive Arboreal Types 









JJICl( 1 p/lhS 



wl 



CA 



Q1 



01 



Phaldiigiftta 



21 



71 



34 



Nolhodccfcn 



1 1 





34 



More Specialized Arljoreal Ty])e 









Tupaia 



5 . 0 



29 . 5 



o4 



Secondarily Arboreal (cliinbiiif;' by use of claws) 









Paraniyfi 





on 

 oO 



32 





24 



SO 



33 



(_ ( 1 C OU pU >l \ — / oTo.s) 



94. 



73 



30 



Cliolo'pus 



31 



1 63 



52 



Primitive Primate Types 









Xothdrctiis os-lmnri, Xo. 11170 



20 



/ 1 



35 



" iciiclirosuK 



24 





32 



Addpi^i (.') iiidgiiux 







3S 



Lrjtili'iii ur 



1 0 



Ow 



Q 1 



o4 



J ,,,, 





oD 



-iO 



" rdriii.s 



26 



108 



41 



Fropiihi'ciis cofpicrclli 



23 



94 



40 



Brachiatiiifi" Types 









Ilnpdic 



10 



46 



46 



Cvhiis 



09 



]0S 



49 



Alnudlld 



30 



162 



54 



Mavdvus 



2") 



146 



58 



Ccrrnrrhtis 



22 



122 





Aiilhnipoi.ilhiTNs 



65 



324 



50 



IJylohalr.s 



27 



226 



84 



Homo 



54 



326 



60 



These figures demonstrate the following facts: 



(1) Semifossorial humeri are very short and broad. 



(2) A primitive ambulatory type has about the same index (32) as the most primitive arboreal type 

 (31), but progressive, cursorial, unguiculate types exhibit a marked elongation of the humerus, 

 the index rising to 51 in Cynwlurus. 



(3) The really primitive arboreal types have the humerus of moderate width (index 31-34), but in 

 advanced arboreal types the humerus invariably lengthens to a greater or less degree. 



(4) In those secondarily arboreal forms which use the large compressed claws in chnging the humerus 

 is moderately wide. 



