PHARSOPHORUS 213 
of the talonid of the lower molars, which in Pharsophorus 
have no basin and consist of a single cusp; and, lastly, in 
the symphysis of the lower jaws being ligamentous, whereas 
in the two preceding genera, it is fused. Pharsophorus 
is probably ancestral to Borhyaena. In the case of Probor- 
hyaena, only a mandible, with the canine and premolars 
3 and 4 intact, has been found. The fourth premolar is 
more reduced than in other genera, but, until more teeth 
are known, its affinities can not be at all closely determined. 
SL 
Um. Lim. 
Fig. 138. Diagram ofa generalized upper molar, U.m., and a lower molar, L.m., of Borhynidae; 
a.s.,ant. style; hid., hypoconulid; mt., metacone; mid., metaconid; pa., paracone; pad., paraconid; 
pr., protocone; prd., protoconid; td., talonid. 
Pharsophorus Ameghino 
Pharspohorus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 502. 
The genus was founded on a lower jaw with premolar 
3 to molar 3 in position. We found beside the above an 
upper jaw with premolar 3, and molars 2 and 3 complete 
while premolar 4 and molar 1 are more or less fragmentary ; 
from which the following generic characters may be made 
out. ‘The incisors are tiny; the canine very large, equal 
to that of Borhyaena; the upper and lower premolars pro- 
gressively smaller from front to back. Upper premolar 3 
is a simple two-rooted tooth, the crown consisting of a 
single blunt central cusp. On the upper molars the proto- 
cone is not developed as a cusp, though the third inner root 
