518 THE MAMMALIA OF THE UINTA FORMATION. 



imal and distal faces are too much worn to admit of description. Another specimen 

 (Fig. 6a) shows a prominent internal malleolus and strong spine. 



The tarsus (Figs. 8-8Z)). The well-preserved astragalus and calcaneum are of 

 great interest. Their relations to those of Palmosyops and Titanotheriam are fully 

 discussed in the next section. The pi*incipal features of the calcaneum are the 

 extremely narrow, deep and elongate tuber calcis, which has an unusually flattened sec- 

 tion ; there is also a distinct fibular facet, and the calcaneum also forms part of the 

 tibial trochlea. The three astragalar facets, the ectal, sustentacular and inferior, are 

 entirely distinct. The astragalus rests upon over one-third of the upper surface 

 of the cuboid. These elements of the ankle joint indicate that Dlplacodon was of 

 much less bulky proportions than Titanotherium. 



Comparative Measurements of the Skeleton, in, Cm. 



Palaosyops. Diplaeodon. Titanotheriam. 



(?) Fifth cervical vi'riclini, antiTO-posterioi- 3.2 4 6.5 



" " " transverse 4.3 6.7 9 



(?) Ninth dorsal vertebra, antero-posterior 3.7 6.5 6.5 



transverse 4.7 5.7 10 



Lumbar vertebra, antero jiosterior 4.7a 6 7 



transverse 89a 6.3 10 



Total length of scapula, estimated 27 60e 72a 



Length of humerus 30.5 45e 67.2a 



" " radius 25 35 65a 



" third metacarpal 11 18 24a 



Width of carpus 6.7 10 



Depth" " 4 8e 11.2a 



Total length of innominate bone 41 61 78a 



Length of femur 33 5 46e 



" tibia 27.5 33 



Width of tarsus 0.5 8.5 14.5a 



a = appro.ximate measurement. e = estimated. 



The PalceosyojhH measurements are taken from the middle size species (P. pahc- 

 dosus), which predominates in the "Western Bridger basin, and while taken from dif- 

 ferent individuals are probably very nearly correct in proportion. Tlie Diplaeodon 

 measurements, with the exception of the femur, tibia and tarsus, are also from por- 

 tions collected together and belonging to one individual. The Titaaotherlum verte- 

 bral measurements are from a single individual, but the other parts are taken from a 

 number of individuals. The P. major of the Bridger is fully one-fourth larger than 

 the above si)ecies. 



ISECTOLOPUUS S. & 0. 



Isedolojjhns is a small tapiroid, slightly lai'ger but with shorter limbs and feet 

 and more spreading digits than the Uinta 2\/)>lopi(i^. 



