--------------+-------+-------+---------+---------+----------+------------ Pharsophorus |Deseado| 1 4 3|vestigal |Protocone|Very small|Ligamentous | |-------| |vestigal |No basin | | | 1 4 3| |Paracone |One post. | | | | |Ant. ext.| cusp | | | | | style | | --------------+-------+-------+---------+---------+----------+------------ Proborhyaena |Deseado| | | | |Fused | |-------| | | | | | 1 4 3| | | | -------------------------------------------------------------------------- From the foregoing, it will appear that _Pharsophorus_ approaches _Borhyaena_ and _Prothylacynus_ in the structure of its upper molars, being, however, nearer to the former, and the same is true of the structure of the talonid; but _Pharsophorus_ differs markedly from both in retaining the metaconid as a small cusp on the side of the protoconid on all of the lower molars; also in the extremely small size of the talonid of the lower molars, which in _Pharsophorus_ have no basin and consist of a single cusp; and, lastly, in the symphysis of the lower jaws being ligamentous, whereas in the two preceding genera, it is fused. _Pharsophorus_ is probably ancestral to _Borhyaena_. In the case of _Proborhyaena_, only a mandible, with the canine and premolars 3 and 4 intact, has been found. The fourth premolar is more reduced than in other genera, but, until more teeth are known, its affinities can not be at all closely determined. [Illustration: Fig. 138. Diagram of a generalized upper molar, _U.m_., and a lower molar, _L.m_., of Borhynidae; _a.s_., ant. style; _hld_., hypoconulid; _mt_., metacone; _mtd_., metaconid; _pa_., paracone; _pad_., paraconid; _pr_., protocone; _prd_., protoconid; _td_., talonid.] =Pharsophorus= Ameghino Pharsophorus Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 502.