560 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXXI. 



The .study of orano- crania as a whole inipresse.s one with the high 

 degree of individual variation and with the role played by the muscles 

 and teeth in modifying various parts. As both of these agencies are 

 mainly connected with the kind of food, the plausible suggestion forces 

 itself upon the mind that a prolonged change, la.sting- through a num- 

 l)er of generations, to food requiring much less mastication should 



Fig. v.— .Mandible of adult male orang (Cat. No. 1421S1 U. S. N. M.). x, A supernumerary tooth; 



//, IRREGULARITY OF THE PREMOLARS. THE RIGHT RAMUS EXHIBITS ONLY TWO MOLARS. 



greatly modify the whole orang skull. It should also })ring it nearer 

 to the human type, for the features by which the orang cranium differs 

 most from the human are with few exceptions exactly those produced 

 by greater teeth and nmscles of mastication. 



As this paper goes to print word is received from Doctor Abbott 

 of a shipment to the National Museum of further material, consist- 

 ing of eighteen crania and skeletons of orangs from Sumatra; these 



