42 THE DESEADO FORMATION OF PATAGONIA 
complete, and the right hind limb complete except for 
the femur. In general, the animal ‘is about ? the size of 
Theosodon garrettorum, but in parts varies 
from this as follows. The lower jaw is 3, 
2 
the vertebrae are = in length, the hind leg 
oO 
cf oe es 5 
is ; in length but ? in diameter of bones, 
: while the metatarsus is only 3% in length. 
Fig. 14. Upper mo- This makes an almost plantigrade form of 
lar. 2 of the right 3 . 
side—natural size, heavy, clumsy proportions. 
after Ameghino. r aks 
Of the upper dentition we know only what 
Ameghino has given us. The molar is distinguished by 
the presence of both the protoconule and metaconule, by 
the development of the posterior cingulum and by the 
presence of three external styles. 
MEASUREMENTS 
Upper premolar 4, length 12 mm., width 15 mm. 
Upper molar 2, length 14 mm., width 17 mm. 
In the lower dentition, none of the teeth are reduced, 
and all are in a continuous series, except that there is a 
Fig. r5. Right lower dentition—natural size. 
small diastema either side of pm. 1. The incisors are 
simple, compressed teeth, with but a trace of a cingulum. 
The canine is incisiform and a trifle larger than the incisors. 
Premolar 1 is also incisiform, and is isolated by a small 
diastema on either side. The second premolar is longer 
and wider than the first, and begins to show molariform 
characters, the anterior portion being composed of a high 
compressed cusp, the posterior portion by a low crescent 
on which but one cusp is fully developed. The third pre- 
molar is composed of two complete crescents, and has the 
