No. 475] OCCIPITAL CONDYLES IX MA.MMAfJA 



483 



they are usually placed under the cranium and directed di)\vn\vard. 

 They are always widely separated, except in some of the lemur-. 

 Occasionally the odontoid process articulates with the skull (Honu 

 Cercocebus, some lemurs); no median condyle occurs. On the 

 median part of the condyles there is usually a depression, wliicli 

 in some forms becomes a sharp notch. 



In some of the mammals fHytena, Tragulus, Equus, ( )\ is, ( "ainc- 

 lus, Figs. 10, 11, and 12, r/), the articular surface of the condyle^, 

 instead of having a continuous curve, possesses a ridge runniit:^' 

 obliquely outward and upward from about the middle of the iinu-r 

 border of the condyles. Xo explanation is offered for this peculiar 

 condition as it apparently reduces the efficiency of the condylar 

 articulation. The habitual position of carrying tiie head, and its 

 direction with reference to that of the atlas, will {)n)l)al>ly oilVr 



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