PARASTRAPOTHERIUM 143 
Ameghino has described several genera, which make 
a progressive series and show a constantly progressive 
variation as far as they are known. 
GENUS FORMATION FORMULA 
Albertogaudryi Casamayor ; i 3. Post. inner and post. 
I . . 
2 median. cusps isola- 
ted. 
Astraponotus Astraponotus i232 3. Post. inner cusp, uni- 
aN ted with wall making 
small lobe. 
Parastrapotherium Deseado and Colpodon #123 Post. lobe large, also 
Se i a strong crista. 
Astrapothericulus Astrapothericulus as 
31253 
Astrapotherium Santa Cruz S228. 
3s 
In the Deseado beds, beside Parastropotherium, Ame- 
ghino has described Liarthrus, based on an upper second 
premolar and part of another tooth, but I can see no 
structural variation from Parastropotherium or indeed from 
P. holmbergi; so 1 consider this genus as a synonym. As 
to the genus Traspoatherium, 1 can not see in it any reason 
for making a genus separate from Parastrapotherium. 
Parastrapotherium Ameghino 
Parastrapotherium Amegh., 1895, Bol. Inst. Ceog. Argen., t. 15, p. 636. 
Parastrapotherium Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 449. 
Liarthrus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 641. 
Liarthrus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 451. 
Traspoatherium Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 641. 
Traspoatherium Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 450. 
The genus, in general, is similar to Astrapotherium, so 
that Gaudry considered it the same, but Ameghino has 
distinguished it by the tushes being relatively of smaller 
size, the lower incisors larger, and by the presence of pm. 3 
