1884.] 23 [Cope. 



are discrete, as in the hog ; and the bones of the feet correspond in number 

 with those of this animal. In 1873, Professor Marsh confirmed these 

 statements as regards the metacarpal bones,* and added " that the navicu- 

 lar and cuboid bones were loosely coosified or separate." In 1884-j- I gave 

 a fall account of the structure of the limbs in this genus. I mentioned a 

 peculiar feature of the carpus, viz. : that the os lunare is supported below 

 by the inward extension of the unciform, so that the magnum is below the 

 scaphoideum. I also showed that the cuneiforms are distinct, and that 

 the entocuneiform is wanting. 



Eucrotaphus Leidy. 



I have already stated that this genus is tetradactyle anteriorly and pos- 

 teriorly.^: I now add that the structure of the limbs and feet is in other 

 respects like that of Oreodon. This is true of the inner extension of the 

 unciform, so that the magnum is below the trapezoi'des. The inner side of 

 the latter bone in the Eucrotaphus pacificus, is so excavated, that there was 

 plainly a free trapezium of small size. In the posterior foot the entocunei- 

 form is wanting, and the mesocuneiform is distinct from the ectocuneiform. 



Merycochcerus Leidy. 



The first information of the foot structure of this genus is contained in 

 my paper on the Oreodontidse above cited. || The fore and hind feet are 

 there stated to be tetradactyle. I now add that in the M. montanus Cope, 

 the os magnum is entirely below the scaphoid, and that there is a distinct 

 trapezium. The posterior foot is constituted as in Eucrotaphus ; I also 

 observe that the navicular has a peculiar little facet on its distal face near 

 the front of the external edge. This fits a corresponding facet which 

 forms the proximal surface of a ledge, which extends from front to rear on 

 the inner side of the cuboid. In Eucrotaphus pacificus the arrangement is 

 similar, excepting that the ledge of the cuboid is interrupted at the middle 

 by a deep excavation. In Merychyus arenarum the cuboid is like that of 

 MerycocJmrus montanus in regard to this ledge. 



Merchyus Leidy. 



The limbs and feet in this genus are quite as in Merycochoerus. The 

 species which I have examined is the M. arenarum Cope. 



Leptomeryx Leidy. 



We possess as yet no information regarding the limbs and feet of this 

 genus. It is therefore fortunate that I obtained in the White River bed 

 of North Eastern Colorado, in 1879, a nearly entire skeleton of the L. 

 evansi Leidy. The bones were all found close together, and belong to 

 two individuals, and are without admixture of those of any other species. 



* Amer. Jour. Sci. Arts, p. 409 ; Marsh does not credit Leidy with his previous 

 observations, 

 t Proceeds. Amer. Philos. Society, Pal. Bulletin, No. 38, pp. 508—10. 

 t Loc. cit., p. 504. 

 || Proceeds. Amer. Philos. Society, 1884, p. 504. 



