[Illustration: Fig. 21. (Half tone.) Restoration of Protheosodon coniferus to show the relatively short limbs, and heavy build as compared with Theosodon—⅕ natural size.] RESTORATION In order to get a comparison of what is known of this form with _Theosodon_ I have outlined a restoration of the animal as a whole, realizing that some essential parts are lacking, but the general proportions can hardly vary greatly from those given. It appears, first, that this form has an unusually short back. Though the limbs and lower jaw are ⅗ the length of those of _Theosodon garrettorum_, the vertebrae are ½ as long. I have assumed that the number of vertebrae would prove to be the same as in _Theosodon_. While the limb bones are ⅗ as long as in the _Theosodon_, they are relatively half again as heavy and with the processes much more developed. The greatest difference is found in the tarsus which is only ⅓ as long as that of _Theosodon_, though relatively as heavy, and the foot was carried in a nearly plantigrade position the heel raised but a little from the ground, though the anticular ends of the metatarsals and the phalanges indicate that there was a considerable freedom of movement of the various elements. The form seems to be fairly close to the ancestral types such as _Lambdaconus_ of the Casamayor, the limbs of which, however, are entirely unknown, but I should expect that when found these earlier forms would prove to be approximately plantigrade. =Coniopternium= Ameghino Coniopternium Amegh., 1895 Bol. Inst. Geog. Argen., t. 15, p. 632. Coniopternium Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 453. The genus is based on a calcaneum and astragulus of the macrauchenid type, but of unusually large size. The real generic characters are not evident in the description, but the presence of these bones, and of three cervical vertebrae, which we also found, indicating a macrauchenid of about the same size, are evidence that a form larger than the Santa Cruz representatives will turn up in the Deseado beds, for which this name may be reserved. The material is described under the specific name _C. andinum_. =Adianthidae= Ameghino This family is based primarily on the genus Adianthus of the Santa Cruz to contain some macrauchenid-like forms which, however, are of much smaller size, and differentiated by the narrow character of the teeth and their early tendency to hypsodonty. It seems to be a valid series of dwarf types, which are all scarce and known only by the most fragmentary remains. Two genera are described from the Deseado, _Tricoelodus_, peculiar in having the posterior lobe of the lower molars somewhat subdivided so that the tooth appears three-lobed; and _Proadianthus_, known only by premolars which however show an unusual development of the styles on the inner side of the teeth. =Tricoelodus= Ameghino Tricoelodus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 454.