CHAPTER x] 
ASTRAPOTHERIA 
THIS group 1s composed of large, long limbed creatures, 
with a highly specialized dentition, in which the canines 
of the upper jaw are developed into great curved tushes, 
resembling those of Pyrotherium; while the canines of the 
lower jaw are compressed in the antero-posterior diameter 
and protrude laterally, like those of pigs. Upper pre- 
molars 1 and 2 are reduced or lacking, while pm. 3 and 4 
are also reduced, but usually retained. The upper molars 
are brachydont, and have a crown very like that of the 
molars of homalodontotheres. 
The lower incisors are small, proclivious, and set at 
intervals around the broad semicircle of the front of the 
fused lower jaws. The lower canines are permanently 
growing teeth, smaller than the upper canines, project 
laterally, and have the tips recurved. Premolars 1 and 
2 are usually lacking, pm. 3 more or less reduced, and pm. 
4 is a normal, short, molariform grinder. The lower 
molars have the same basal pattern as in Tovxodonta, 
the crown carrying two crescents with a plump pillar in 
the basin of the posterior crescent, the pillar, however, 
being situated far forward near the anterior horn of the 
redr “Crescent. 
Lydekker made an order Astrapotheria including the 
Astrapotheria and Homalodontotheria, but as the dentition 
of the two groups is so different, because of the enormous 
enlargement of the frontal region, and because of the 
reduction of the premolars, | am convinced that these 
two groups represent totally divergent lines of develop- 
ment; and I have therefore made each of the groups a 
. separate suborder. 
