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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL.83 



constricted between the anterior and posterior portions than m the 

 modern material observed. On the distal surface the posterior por- 

 tion of the facet for the third metacarpal averages distinctly narrower 

 than in the Equus material. 



Ij til 



III ill 



''ifm 





m-r- 



anterior and 

 One-fourth 



FIGURE 2i-Plesippus shoshonensis Qidley: A, Articulated left fore foot, U.S.N.M no 13794 

 med'al views; B articulated right hind foot, U.S.N.M. no. 13792. anterior and lateral v.ews. 

 natural size. Hagerman lake beds, upper Pliocene, Idaho. 



The unciform shows marked variation in the relative size and shape 

 of the articular facets and in the length of the process projecting 

 postero-internally. The facet for articulation with the cuneiform in 



