276 UNGULATA 
respects a great contrast to such decadent types as those represented 
by the Tapirs and Rhinoceroses. 
The principal anatomical characters by which the Artiodactyles 
are distinguished from the Perissodactyles are as follows. The 
premolar and molar teeth usually not alike, the former being 
single and the latter two-lobed. The last lower molar of both first 
and second dentition almost invariably three-lobed; and the first 
tooth of the upper cheek series always without a milk-predecessor. 
Nasal bones not expanded posteriorly. No alisphenoid canal. 
Fic. 99.—Bones of right fore foot of existing Artiodactyles. A, Pig (Sus scrofa), x4; B, 
Red Deer (Cervus elaphus), x}; C, Camel (Camelus bactrianus), x}. C, Ulna; R, radius; + 
cuneiform; /, lunar; s, scaphoid; u, unciform ; m, magnum; td, trapezoid; tin, trapezium, 
From Flower’s Osteology of Mammalia. 
Dorsal and lumbar vertebre together always nineteen, though the 
former may vary from twelve to fifteen. Femur without. third 
trochanter. Third and fourth digits of both feet almost equally 
developed, and their ungual phalanges flattened on their inner or 
contiguous surfaces, so that each is not symmetrical in itself, but 
when the two are placed together they form a figure symmetrically 
disposed to a line drawn between them. Or, in other words the 
axis or median line of the whole foot is a line drawn between the 
third and fourth digits, while in the Perissodactyles it is a line 
drawn down the centre of the third digit. Distal articular surface 
