AESINOITHEEITJM. 



59 



This bone is entirely unlike the Proboscidean cuboid. It is more like the cuboid 

 of Uintatherium, but differs from that in several respects — e. g. in the much smaller 

 size of the calcaneal facet. 



The metatarsals are not definitely known, but the collections include a number of 

 short and very massive metapodials which probably belong to the hind foot of this 

 animal. Two of these are shown in text-fig. 35 Of these one (2 A, 2 c) probably 

 belongs to a middle digit. Its proximal articulation (2 a) is gently convex from 

 before backwards, but does not extend quite to the hinder surface of the bone, which 

 is produced posteriorly into a large tuberosity. In front the proximal articulation is 



Text-fig. 35. 



2A 



mt 



i 

 X 2 



Metatarsals of Arsinoitherium zitteli : 1 a, proximal end of lateral metatarsal ; 1 B, same specimen 

 from front ; 2 a, proximal end of middle metatarsal ; 2 c, same specimen from front. 



mt., facet for adjacent metatarsal. | nat. size. 



produced considerably to one side, probably the post-axial, and bears a facet for 



articulation with the next metatarsal [mt.). The shaft of the bone is slightly 



contracted. The distal articulation is wide and consists of two surfaces, both 



convex from above downwards and concave from side to side and meeting at an 



angle on the distal end of the bone. The anterior and larger of these surfaces 



articulated with the first phalange and is limited above by a groove, above which is a 



strong rugose ridge extending across the whole face of the bone and produced 



laterally into tuberosities. The smaller posterior siirface no doubt supported a 



sesamoid or a pair of sesamoids. 



i2 



