1910.] The Condylarthra. 355 



ment of the carpal bones is no longer thought to be primitive (see belo^v and 

 p. 440). 



The small Euprotogonia puercensis (Cope), the Basal Eocene (Torrejon) 

 forerunner of PJienacodus, was descril)ecl by jMatthew (1897, pp. 305-310) 

 and by Osborn (1898, pj). 163-164). It approached nearer to the Insecti- 

 vore-Creodont type in many characters, including the following: 



(1) In the dentition the molar pattern is less removed from the tri- 

 tubercular type than is the case in PJienacodus {vide supra). 



(2) Euprotogonia was only about half the size of Phenacodiis primcevus, 

 i. e., about nine inches high at the withers. 



(3) In the carpus the magnimi and trapezoid are small and the lunar 

 retains a little of its primitive contact with the unciform (Matthew, 1897, 

 p. 320, infra, p. 446). 



(4) The astragalus retains a distinct astragalar foramen (lost in PJiena- 

 codus) and shows a decided approach to the Creodont astragalus, e. g., as 

 represented by Sinopa. 



(5) The hind foot was probably semiplantigrade (Matthew). 



(6) The ungual phalanges are narrower than in PJienacodus, "inter- 

 mediate between claws and hoofs" (Osborn). 



The more precise derivation of the Euprotogonia-Phenacodus line is 

 unknown. 



MeniscotJierium. 



Presumably specialized cJiaracters. — This Lower Eocene genus (figiu-ed 

 in Cope's ' Tertiary Vertebrata,' plates xxv f and g) appears to be an isolated 

 form widely removed from PJienacodus by the possession of many specializa- 

 tions. Its buno-lopho-selenodont upper molars (figured by Osborn, 1907, 

 p. 184, fig. 183) are remarkably elaborate in pattern for a Lower Eocene 

 Holarctic Ungulate. The main external cusps and the large protoconule 

 are crescentic, the metaconule obli(juely lophoid and confluent with the 

 large hypocone, the para- antl mesostyles well developed. The fourth 

 upper premolar and the third molar are like m^ and m^ except that they 

 lack the postero-internal cusp. The fourth lower premolar is molari- 

 form and the metaconid on the lower molars is reduplicate. The third 

 lower molar lacks the third lobe. The incisors and canines are reduced 

 in size. The skull is brachycephalic, and very broad across the orbits, 

 which are large. The brain case is relatively wider than in PJienacodus. 

 The long flattened femur has the large third trochanter well down on the 

 shaft and continuous with a ridge running down to the external condyle, 

 i. e., much as in PantoJamhda. The calcaneum is large and has a long 

 tuber calcis; the small, wry-necked astragalus is figured as being without 

 an astragalar foramen. 



