PLEUROCOELODON 131 
T. biconus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18. p. 
484. 
This species is based on two lower premolars, said to be 
the same size as 7. angustus, but with the pillar larger. 
Pleurocoelodon Ameghino 
Pleurocoelodon, Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 645. 
Pleurocoelodon, Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 484. 
This genus is distinguished by the absence of the style 
on the anterior external margin of the upper molars, in- 
Fig. 89. P.wingei—natural size; A, first molar; 
B, third molar. 
stead of which the external face is excavated medianly. 
Two species are described, based on isolated upper teeth. 
P. wingei Ameghino 
P. wingei Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 645. 
P. wingei Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 485. 
This species is founded on a couple of isolated molars, 
probably belonging to the same individual. The following 
measurements are given: 
Upper molar 1, length 22 mm., width 26 mm. 
Upper molar 3, length 24 mm., width 29 mm. 
P. cingulatus Amegh., loc. cit. above, is based on an in- 
complete upper molar, probably the second, which is dis- 
tinguished by having the internal cingulum excessively 
developed. It measures 30 mm. in length. 
