68 SCOTT. [Vol. V. 



but the narrowness of this facet, the absence of any groove on 

 the outer side of the tibia, and the presence of a large rugose 

 surface in place of it, make it probable that though the reduc- 

 tion of the fibula had begun, it was by no means complete. 



The tarsus of Leptotragalus is very like that of Pcebrotherium. 

 The calcaneum is long and compressed and of less vertical 

 extent {i.e. from the dorsal to the plantar side) than in the 

 Miocene genus. The astragalus is high and narrow, with the 

 proximal trochlea deeply and widely grooved. The cuboidal 

 surface is very narrow. The cuboid is remarkably high, narrow, 

 and deep. Both the surfaces for the astragalus and calcaneum 

 are narrow, the latter a little the broader of the two ; the poste- 

 rior hook is longer and less massive than in Pcebrotherium ; 

 the distal surfaces for mts. IV and V are very much as in that 

 genus. 



The mts. Ill and IV are enlarged, but, though broken, 

 obviously elongate and slender ; their distal ends are almost 

 exactly like those of Pcebrotherium . Judging by the fossae upon 

 the median metatarsals, it appears probable that the lateral 

 ones are not quite so much reduced as in the White River 

 type. 



The phalanges of the first row are very slender and rounded 

 and the unguals are long, compressed, and pointed like those of 

 the antelopes. 



In Pcebrotherium the ilium has a very long and narrow pe- 

 duncle and a plate, which apparently was not much expanded ; 

 the ischium is also slender and compressed and without the 

 arched prominence above and behind the acetabulum, so prom- 

 inent in the recent forms. The femur is very tylopodan in 

 appearance ; but the bridge connecting the great trochanter 

 and the head is shorter and narrower, and the great trochanter 

 less massive there than in the living forms. The condyles are 

 smaller and less prominent and the rotular trochlea wider and 

 shallower; a pit for the insertion of the plantaris muscle is 

 present. 



The tibia is long and slender, with very prominent and ex- 

 tended cnemial crest. The distal facets for the astragalus are 

 partly interrupted on each side of the tongue. The fibula is 

 very much reduced, the shaft having disappeared, and the distal 

 end moved beneath the tibia ; but the groove for it on the latter 



