316 THE OSTEOLOGY OF ELOTHERIUM. 



concave antero-posteriorly and convex transversely. In one species of Elotherium, not 

 yet identified, a somewhat different proportion of these cuneiform facets is found ; the 

 mesocuneiform facet is larger and that for the entocuneiform smaller and in shape and in 

 position more as in the recent pigs. 



Kowalevsky's figures ('76, Taf. XXVII, Figs. 34, 37) do not display any character- 

 istic differences in the structure of the navicular between the American and the European 

 species of Elotherium. In Anihracotherium (Kowalevsky, '73, Taf. XI, Figs. 48, 59) the 

 navicular has a long, massive and rugose hook, given off from the plantar side ; the facet 

 for the ectocuneiform is relatively smaller and that for the mesocuneiform much larger 

 than in Elotherium, and the two surfaces are distinctly separated. Much the same 

 description will apply to Stis. In Hippopotamus the navicular is very low and broad, and 

 its distal facets arc well distinguished. 



The entocuneiform is in shape not unlike the rudimentary, nodular metapodials ; it is 

 high, narrow and compressed, thickest proximally and tapering distally to a blunt point. 

 The navicular facet is relatively large, and is saddle-shaped, with curves the converse of 

 those which occur on the corresponding surface of the navicular. Distally, there is a 

 facet on the fibular side fur the plantar projection from the head of the third metatarsal. 



This element has not yet been found in connection with Anihracotherium, or with 

 the European species of Elotherium. In Sus it is of quite a different form and decidedly 

 smaller, while in Hippopotamus it is broader, heavier and shorter than in the fossil form. 



The mesocuneiform is firmly ankylosed with the ectocuneiform, but its shape is, 

 ne\ ei'thcless. clearly distinguishable : it does not extend quite so far distally as the latter and 

 is very small, especially transversely, and narrows toward the distal end. Its facet for the 

 second metatarsal is obscurely displayed and it has no contact with the third. In E. magnum 

 (Kowalevsky, Taf. XXVII, Figs. 35, 37) the two cuneiforms are even more completely 

 fused than in the American species. In Anihracotherium the mesocuneiform is separate 

 and has a large surface for articulation with the second metatarsal, as is also the case in 

 Hippopotamus. In Sus this element is likewise distinct, but higher and narrower, and 

 articulates with the second metatarsal more extensively than with the third. 



The ectocuneiform is a large bone, of irregularly quadrate shape; its proximal 

 surface hears a large, plane facet for the navicular, and the distal end is oceujiied by a 

 still larger surface tor the third metatarsal : the latter is abruptly contracted toward the 

 plantar side. On the tibial side and distal to the mesocuneiform is a minute lateral facet 

 for the second metatarsal. The contact with the cuboid is restricted to two facets near 

 the proximal end, one dorsal and the other plantar, of which the latter is the smaller, but 

 thi' more prominent. In E. magnum this bone is very much as in the American species, 

 but the distal facet is of a different shape, not contracting so much toward the plantar 



