PRONESODON 125 
MEASUREMENTS 
Skull, width across the zygomatic arches 148 mm. 
Skull, width across opposite m. 3 (outside) 73 mm. 
Upper dentition, molar 2, length 25 mm., width 13 mm, 
Upper dentition, molar 3, length 23 mm., width 12 mm. 
Lower dentition, incisor 3, length 13 mm., width 7 mm, 
Lower dentition, molar 2, length 20 mm., width fey seibin 
Proadinotherium angustidens Ameghino 
P. angustidens Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 467. 
This is based on a single lower tooth, which is considered 
either pm. 4 or m. I, and measures 13 mm. long by 45 mm. 
wide. 
Pronesodon Ameghino 
Pronesodon Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 626. 
The genus is said to resemble Proadinotherium, but with 
the caniniform incisors proportionally much shorter. An 
associated calcaneum is shorter than that of Adinothertum 
and longer than that of Nesodon. 
Two species are described. 
Pronesodon cristatus Ameghino 
P. cristatus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 626. 
P. cristatus Amegh., 1897, Bol. Inst. Geog. Argen., t. 15, p. 467. 
This species is very imperfectly known, is characterized 
by a large external anterior style, molars said to be 15 mm. 
wide. 
Pronesodon robustum Ameghino 
P. robustum Amegh., loc. cit. above. 
This is a larger species, of which the three lower molars 
are known, and which measure 16, 22, and 30 mm. in length 
respectively, while they are 9-10 mm. wide. 
