1898.] SCOTT — ON THE SELENODONT ARTIODACTYLS. 75 



functional digits, though the lateral metacarpals are already very 

 much more slender than the median pair. The fibula is complete and 

 not coossified with the tibia at any point, but its shaft is so reduced 

 as to be a mere thread of bone. The pes contains two functional 

 metatarsals, iii and iv, while Nos. ii and v are long, filiform and 

 splint-like rudiments to which, apparently, no phalanges are 

 attached, but this is still doubtful. The phalanges of the functional 

 digits resemble those of Poebroihei^ium, and the unguals have the 

 same long, pointed and slender, antelope-like shape. 



There can be very little doubt that Parai7ieryx is the direct and 

 immediate ancestor of the White River Poeb7'othe7Hiim, which it so 

 much resembles, and thus it holds an important place in the main 

 line of Tylopodan descent. 



Leptotragulus Scott and Osborn. 

 Proc. Amer. Phil. Soc, 1887, P- 258. 



In a former account of this genus, ^ the type of which is a frag- 

 ment of the mandible containing p -3, 4 and m y, I made the 

 mistake of referring to it certain limb and foot bones which, it is 

 now apparent, belong to the very distinct genus Parameryx, from 

 which Leptotragulus differs in the form of the premolars and in the 

 presence of diastemata. At present I am not able to refer to the 

 latter genus any of the newly acquired material, and hence can add 

 nothing to my original account'- of it. It differs but compara- 

 tively little, however, from the following genus, the structure of 

 which may be very fully described. 



Merycodesmus, gen. nov. 



Dentition unreduced; I. f, C. \, P. f, M. |; upper incisors 

 conical, pointed and slightly recurved ; upper canine large, com- 

 pressed and thick ; lower canine incisiform ; p -I- near canine, with 

 diastema behind it ; p ^ with deuterocone ; p y caniniform and 

 opposing upper canine ; p y with large deuteroconid. Molars com- 

 posed of four crescentic lobes, m -3 with fifth lobe. Forehead 

 elongate and lozenge-shaped, sagittal crest short, as in Parameryx ; 

 mandible with very extended angle. Manus and pes having four 



^ Trans. Amer. Phil. Soc, Vol. XVI, p. 479. 

 2 Proc. Amer. Phil. Soc, 1887, p. 258. 



