In the Deseado beds, beside _Parastropotherium_, Ameghino 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 I consider this genus as a synonym. As to the genus _Traspoatherium_, I can not see in it any reason for making a genus separate from _Parastrapotherium_. =Parastrapotherium= Ameghino Parastrapotherium Amegh., 1895, Bol. Inst. Geog. 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 in the lower series. The Deseado forms are also of considerably larger size than the Santa Cruz. Our material includes a pair of lower jaws, two scapulae, the humerus, and the lower end of the femur. No skull has been found in the Deseado. Those from the Santa Cruz are enormously swollen over the orbits, the massive bone making a skull wholly unique. The lower jaws are similar to those of _Astrapotherium_, except that the rami are deeper. The front ends are fused and expanded making the anterior much enlarged, and causing the incisors to stand at intervals as in _Coryphodon_. The symphysis is massive and prolonged backward nearly to premolar 3. The rami are plump and unusually thick. [Illustration: Fig. 102. Upper dentition of Astrapothericulus iheringi—½ natural size.] Of the upper dentition, Ameghino figures only the first molar and the canine. I have given Ameghino’s figure of the upper dentition of _Astrapothericulus_, to indicate what this would be like, for the variation is only slight. The canine is a great tush, not unlike the incisor-tush of _Pyrotherium_, oval in cross section with the greater diameter from front to back. The first and second premolars have disappeared. Premolars 3 and 4 are greatly reduced. The molars are very like those of _Asmodeus_, large brachydont grinders, composed of an outer wall, and an anterior and posterior lobe. The external cingulum is a trace only, and the internal cingulum is developed in varying degrees. The basin is deep and subdivided by a crista which rises from the external wall, and as the surface is worn off unites with the anterior lobe, cutting off a small pit. Behind the posterior lobe is a small basin, bounded in the rear by a second crista from the rear end of the external wall, which, as the tooth is worn down, unites with the posterior lobes, cutting off a small posterior pit, suggestive of that of homalodontotheres.