COI^ YPHOD ON 207 



by Professor Marsh ; the numerous points in common possessed 

 by the members of both families forbid their separation more 

 widely than as families. 



The earliest types of Amblypoda belong to the genus 

 Pantolamhda, of which the species P. bathmodon was about four 

 feet in length. As restored it seems to have had proportionately 

 short fore- and hind-limbs, and it had a long tail. It was 

 apparently plantigrade, and would have had not a little likeness 

 to a carnivorous type. The skull has no air cavities, such as are 

 developed in the later typos from the Lower Eocene, e.g. Cory- 

 phodon; Pantolambda is from the basal Eocene. The frontal 

 bones show no trace of the horns that are developed in subsequent 

 forms ; the nasals are comparatively long ; the zygomatic arch is 

 slender. The molar teeth are in the primitive form of trituberculy, 

 and the premolars, as is so often the case with primitive animals, 

 are unlike the molars in form, being less markedly selenodont. 

 As to the vertebral column, the dorsal vertebrae appear to have 

 had short spines, which argues, as it does also in the case of the 

 larger and heavier Coryphodon, a feebleness in the development of 

 ligaments and muscles supporting and moving the head. The 

 scapula seems to have the same peculiar leaf-like form that it has 

 in the later Corypliodon} This primitive type shows an entepi- 

 condylar foramen in the humerus. It is interesting to observe 

 that the posterior border of the ulna is convex, as in the Creodonts, 

 and in the early Condylarthrous form Euprotogonia. In the sub- 

 sequently-developed Amblypoda, as in the later Condylarthra, 

 that bone acquires a concave outer border. In the carpus the os 

 centrale is distinct. In the femur the third trochanter is well 

 formed ; it gradually dies out in later Amblypoda. The fibula 

 articulates with the calcaneum. This species, according to Osborn, 

 " typifies the hypothetical Protungulate, being more primitive 

 than either Euprotogonia or Phenacodus." " 



The genus Coryphodon is known by a large number of species, 

 of which the first was discovered in this country, and was repre- 

 sented merely by a jaw with some teeth. This was named by Sir 

 E. Owen 0. eocaenus, and was dredged up from the bottom of the 

 sea off the Essex coast. A second specimen consisted of a single 



' The scapula of P. bathmodon is unknown. 



* For the structure of this genus and of Coryphodon, see Osborn, Bull. Amer. 

 Mus. Nat. Hist. x. 1898, p. 169. 



