FOSSIL VERTEBRATES —MAMMALIA 827 
stands far in front of the remainder, and has the appearance of 
a canine. The genus appears to be confined to the latest depos- 
its of the Tertiary in the United States, and is found in the cave 
deposits of the southern states. The animal reached the size of 
an Ox, 
Mylodon, another form is distinguished from the others by 
the appearance of slight irregularity in the form of the teeth; 
instead of straight peg-like form, they are triangular, and the 
teeth of the lower jaws are somewhat figure eight shaped in out- 
line. This genus was fully as large as the Megatherium and had 
even a greater geographical range, species being known from the 
pampas of the Argentine Republic, and from the caves of Ore- 
gon. 
A very large number of forms have been described from the 
deposits of Patagonia and the Argentine Republic, anda smaller © 
number from other parts of the southern continent, many being 
found on the west coast, to reach which place they must have 
either crossed the Andes, or emigrated down the west coast from 
far up in the United States. The geological range seems to have 
been from the upper Eocene or the Oligocene to the latest Plio- 
cene. 
Glyptodonta.— These were animals in which the body was cov- 
ered by a strong carapace of bone that was made up of many 
small ossicles of different shapes, joining each other by suture, 
The armor was confined entirely to the dorsal surface, there 
being no plastron or ventral plate as in theturtles. The tail was 
large and covered with the same armor as the back. The skull 
was very short and high with a lower jaw of great vertical thick- 
ness. The teeth were elongated in the anterior-posterior direc- 
tion, and the sides of the teeth were marked by deep vertical 
grooves that nearly divided the teeth into three parts. The 
vertebre of the dorsal region were all united into a long tube, 
and the lumbar vertebre were anchylosed with the sacrum, thus 
practically destroying any mobility of the spine. The feet were 
provided with broad, almost hoof-like claws. The animals some- 
times reached a very large size. The whole suborder is extinct. 
