EXTINCT LEMUROIDS 697 
erinaceus, of the upper Eocene of Hampshire, of which the corre- 
sponding teeth are shown in B of the same figure. In this genus, 
according to Dr. Schlosser, the dental formula is i 2, ¢ 4, p 3, m 3, 
or the same as in the existing Twrsius ; but it is not improbable that 
in some instances the first lower premolar may have been developed. 
The upper molars of Af erinaceus differ from those of MZ. antiquus 
by the simpler structure of their columns and the smaller size of 
the external cingulum, which lacks the median cusp found in the 
latter. The angle of the mandible is produced into a large hook- 
like flange which at once 
distinguishes the genus 
from all existing Lemurs; 
and the anterior lower 
premolar is not canine- 
like. M. antiquus is of 
very small size, but the 
larger M. edwardsi of the 
same deposits comes : 
nearer in dimensions to Fic, 332.—The last five right upper cheek-teeth of Micro- 
. cherus antiquus (A) and Microcherus erinaceus (B). Twice 
M. erinaceus. The upper natural size, and natural size. 
molars decrease in size 
from the first to the third, the first and second having a median 
cusp in the external cingulum, by which they are readily dis- 
tinguished from the corresponding teeth of the under-mentioned 
genus Hyopsodus. The third upper molar differs from that of 
Hyopsodus by its small size and the abortion of its posterior columns. 
The skull approximates to that of the living genus Galago, exhibit- 
ing the same inflation of the auditory bulla. The upper molars 
are also not unlike one species of that genus, but the fourth upper 
premolar has but one outer cusp, as in Chirogaleus. 
The small ./naptomorphus, from the North American Eocene, 
has a skull of about the same size as that of the smallest species of 
Microcherus, but the dental formula is i 2, ¢ 4, p 2, m 3, and the 
upper molars are of the tritubercular type. 
The well-known Adapis (Aphelotheriwn or Paleolemur), of the 
Upper Eocene of France and England, differs from all existing 
Lemuroids in possessing four premolars!; the dental formula being 
i 2,¢4,p4,m 3. The fourth upper premolar has two outer cusps, 
and the upper molars (Fig. 333) resemble those of Lepidolemur and 
Hapalemur, while the lower canine is a well-developed tooth per- 
forming the usual function of biting against the canine of the upper 
jaw. The lower incisors have upright, spatulate crowns, as in the 
true Apes. The skull is said to approximate in contour to that of 
Propithecus. The typical A. parisiensis is of comparatively small 
size, but the species of which the upper cheek-teeth are shown in 
1 One specimen has been seen with only three lower premolars. 
