712 THE BEIDGEE FAUNA. 



position is not certainly known. The tootli in question is very much like 

 that of the Lambdotherium popoagicum, but differs in easily recognizable 

 specific characters. The crest that extends from the posterior inner tubercle 

 reaches to a point between the external lobes, and is therefore longer than 

 in the species named. It also shows a slight tendency to a division cutting 

 off an intermediate tubercle, like the anterior one. The median ribs of the 

 external Vs are more distinct than in L. popoagicum. The anterior and pos- 

 terior cingula are distinct, and the external and internal are neai-ly complete. 

 The crown is low, and the enamel nearly smooth. 



Meaxurements. 



M. 



I auteroijosterior 0.0070 



Diameters of crovrn •? vertical - 0035 



' transverse 0090 



The molar tooth is about the size of that of a raccoon; hence the name. 

 Cottonwood Creek, Wyoming. Bridger Epoch. 



MACRAUCHENIID^. 



But one genus of this family is knoAvn at the present time. The fol- 



3 1 



lowing are the dental characters of Macrauchenia; formula: I. -; C. -; Pm. 



O J. 



4 3 



- ; M. - ; forming an uninteiTupted series. 



The superior molars present two external Ys and two oblique trans- 

 verse crests, somewhat as in Palceotherium. The spinous foramina pierce the 

 neural arches of the dorsal vertebra (Gervais). There is no intertrochlear 

 crest of the humerus, but the carpal facets of the radius are well distin- 

 guished. The internal malleolus is small, but the fibular malleolus is coos- 

 sified with the tibia at an early age, and articulates with the calcaneum. 

 The trochlea of the astragalus is well developed. The lateral digits are 

 large, and the distal keels of the metapodials are continued on the anterior 

 faces of the condyles. 



The position indicated by the above characters is a remarkable one. 

 The uninterrupted dental series and the absence of interti'ochlear humeral 

 crest are primitive features among ungulate Mammalia. The radio-carpal 



