2 04 CONDYLARTHRA PROTOGONIA chap. 



Creodouta. It has, as in Phenacodus, no orbital ring. The 

 humerus resembles that of a Carnivore rather than that of an 

 Ung'ulate. The carpus and tarsus are serial. The fibula articu- 

 lates with lioth the calcaneum and the astragalus, which is not 

 the case with Plicnacodus. It is suggested that these animals 

 are ancestral forms of the Chalicotheres. In the brain the 

 hemispheres do not cover the cerebellum. 



More primitive apparently than Fhcnacodus was the less-known 

 genus Euprotogonia, or Protogonia ^ as it has been called. The best- 

 known species is E. jnicrccnsis, so called from its occun'ence in the 

 Puerco beds of the American Eocene. It was a slender, long- 

 limbed creature, smaller than Phenacodus, with a long and heavy 

 tail as in that animal.' Like Phenacodus it was semiplantigrade, 

 and shows more likenesses to the Creodonta. The skull is only 

 known Ijy a part of the lower jaw with teeth^ and by the teeth of the 

 upper jaw. The vertebrae are not entirely preserved, liut enough 

 . remain to show that the animal had a tail of 1 6 or 1 7 inches, which is 

 a considerable length when compared to its lieight, about a foot at 

 the rump. In the fore-limb the most noteworthy point is that the 

 ulna has a convex posterior border as in the Creodonts, the same 

 border in Plicn.acodus lieing concave. The humerus is slender, with 

 less-marked tul)erosities. The fifth digit seems to have been less 

 reduced. The phalanges seem to have borne horny sheaths some- 

 what intermediate lietween hoofs and claws. The pelvis is 

 described as being, as is also that of Phenacodus, rather like that of 

 the (Jreodonta. The right hind-liml) is known in all its details. 

 It appears that the bones are not serial but interlocking ; this, 

 however, on tlie views with regard to the relations of these two 

 forms of tarsus mentioned on p. 198, does not militate against 

 regarding Euprotogonia as the ancestor of the genus Phoiacodtis. 

 Tlie third toe is the pre-eminent one, the animal thus being 

 Perissodactyle. The lateral digits are larger than in Phenacodus, 

 and tlie metatarsals and the phalanges are sliglitly curved, which 

 is again a Creodont character as compared to the perfectly straight 

 corresponding bones of Phenacodus. It seems evident that this 

 animal is to be looked upon as a more ancient type than Phena- 

 codus, even if not as its actual ancestor. 



Another group of the Condylarthra contains the genus 

 Pertipychus and some others. Periptychus has the full dentition 

 ' See W. t). Matthew, Bull. Amcr. Mus. Kut. Hist. ix. 1897, p. 303. 



