THE OSTEOLOGY OF EL0THEB1TJM. 317 



side (Kowalevsky, Taf. XXVII, Figs. 35). In Anthracotherium (Kowalevsky, '73, 

 Taf. XI, Figs. 48, 59) the ectocuneiform is lower and lias a more extended connection 

 with the second metatarsal. The ectocuneiform of Hippopotamus is low, but very broad, 

 in keeping with the great size of the third digit. In $us this element is not so wide as in 

 Elotherium, and differs from that of all the genera mentioned in having no contact with 

 the second metatarsal, from which it is cut off by the articulation of the mesocuneiform 

 with the third. 



The cuboid is massive and large in all its dimensions, high, broad and thick. The 

 proximal surface is about equally divided between the facet for the calcaneum and that 

 for the astragalus, though the latter is slightly the wider. This facet, which is simply 

 concave antero-posteriorly, is widest near the dorsal border, and in the middle of its 

 course is deeply emarginated from the tibial side. The calcaneal facet is imperfectly 

 divided into two parts, of which the dorsal portion is much the larger, particularly in 

 width, while the plantar portion curves inward so as to lie, in part, behind the astragalar 

 surface. The cuboid is firmly interlocked with the navicular by means of the deeply 

 concave facet on the tibial side near the plantar margin, which receives the projection 

 from the navicular already described. Dorsally the contact between these bones is 

 limited to two small facets, one of which is proximal, and the other is distal on the navi- 

 cular, median on the cuboid, where it helps to form the projection between the navicular 

 and the ectocuneiform ; this prominence is, however, very short. The facets for the 

 ectocuneiform are also dorsal and plantar, and are just distal to those for the navicular. 

 The distal end of the cuboid is taken up by the large facet for the fourth metatarsal, that 

 for the rudimentary fifth being very small and lateral in position. The plantar hook is 

 not long, but is very broad and massive, and bears on its tibial side a facet for the pos- 

 terior projection from the head of the fourth metatarsal. 



In Elotherium magnum (Kowalevsky, '76, Taf. XXVII, Figs. 34-36) the cuboid is 

 not so high in proportion to its breadth as in the American species, and the tendinal 

 sulcus on the fibular side is deeper. The cuboid of Anthracotherium is broader and lower 

 and has, of course, a larger and more distal facet for the fifth metatarsal. In iSus similar 

 proportions recur, and the division of the calcaneal surface into two parts is complete. In 

 Hippopotamus the cuboid is very low and broad, and the astragalar facet is much wider 

 than the calcaneal. 



The metatarsus, like the metacarpus, consists of two functional (iii and iv) and two 

 rudimentary members (ii and v). 



Metatarsal II is a small nodule, which is much compressed laterally and tapers to a 

 point at the distal end ; the articulations are proximally with the mesocuneiform and 

 laterally with the ectocuneiform and mt. iii. 



