698 PRIMATES 



the woodcut is of much larger dimensions. The skull of A. magna, 

 which measures upwards of 4 inches in length, resembles that of 

 A. parisiensis in its general characters, but is modified much in the 

 way that the skulls of larger animals differ from the smaller ones of 

 the same natural group. Thus the brain-chamber and orbits are 

 relatively smaller, the face larger, the muscular crests more 



developed, and the constriction be- 

 tween the cerebral and the facial 

 portion of the skull more marked. 

 These modifications remove the skull 

 in its general characters still farther 

 from the existing Lemurs so much 

 so that M. Filhol refers it and the 

 other species of Adapis to a distinct 

 FIG. m-The left upper cheek-teeth zoologica i type intermediate between 



of Adapis magna, from the Upper Eocene , , 11 i i 



of Hampshire. the lemurs and the pachyderms, to 



which he gives the name of Pachy- 



lemuriens, but later researches do not support this view. As 

 mentioned above, it has been suggested that Ccenopithecus lemuroides 

 is inseparable from Adapis parisiensis, but the postero- internal 

 column of the upper molars is said to be larger. The genera 

 TomitJierium and Nothardus, of the Eocene of the United States, 

 appear to be allied to Adapis, but the second has a larger lower 

 canine. The same deposits have also yielded more or less imper- 

 fect remains of other forms departing more widely from the existing 

 Lemuroid type. Of these Hyopsodus, of the "Wasatch and Bridger 

 Eocene of the United States, has the dental formula i , c ^, p , 

 m f. The quadrituberculate upper molars have well -developed 

 accessory intermediate columns (protoconule and metaconule), and 

 thus resemble those of Microcliwrus ; the external surfaces of the 

 outer columns of their teeth being flattened, with vertical ridges 

 and a distinct cingulum. The third upper molar has its postero- 

 internal column (hypocone) partly aborted, but is otherwise as well 

 developed as the preceding molars. Microsyops, of the North 

 American Eocene, appears to have been 

 an allied form in which there were prob- 

 ably only three premolars. 



The genera Protoadapis and Plesiadapis, 

 from the lowest Eocene of Rheims, may 

 not improbably be regarded as primitive 

 Lemuroids. The loAver molars are quin- FIG. 334. The right upper 

 quetubercular, and not unlike those of cheek-teeth of Pk*u<dapis remen- 



i.-. /, 1,11- i r ^i sis; from the Lowest Eocene of 



Microsyops; the dental formula of the Rheim8 . X |. 3 , 3, 4, premolars ; 



lower jaw is i 2, C I, p 3-4, m 3 in the m, 1, 2, 3, molars. (From Osborn.) 



first-named genus, but in the second the 



dentition is reduced to i j, c ^, p f , m f . In Plesiadapis the lower 



