698 PRIMATES 
the woodcut is of much larger dimensions. The skull of 4. 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 
Fic. 33.—The left upper cheek-teeth_ roolocical type, intermediate between 
of Adapis magna, from the Upper Eocene 
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 Cenopithecus lemuroides 
is inseparable from Adapis parisiensis, but the postero-internal 
column of the upper molars is said to be larger. The genera 
Tomitherium and Notharctus, 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 2, ¢ 4, p 4, 
m 3. The quadrituberculate upper molars have well-developed 
accessory intermediate columns (protoconule and metaconule), and 
thus resemble those of Microcherus,; 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 Kocene, 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 lower molars are quin- iq. 334.—'The right upper 
quetubercular, and not unlike those of cheek-teeth of Plesiadapis remen- 
Microsyops ; the dental formula of the 74)" me Ciera 
lower jaw is 7 2, ¢ 1, 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 2, ¢ 3, p 2, m3. In Plesiadapis the lower 
