PLATE 45 



HUMERUS AND TIBIA OF MERYCHIPPUS ISONESUS SECUNDUS, M. ISONESUS QUARTUS, M. ISONESUS QUINT-US. 

 COMPARISON OF THREE SPECIES FROM THE SHEEP CREEK BEDS, SIOUX COUNTY, NEBR. 



All figures one-half natural size. 



Note the differences in proportion between M. isoncsus secundus and M. isonesus quintus; M. isonesus quartus is 

 intermediate. 



Sheep Creek, Nebr. Middle Miocene 1, 3. Merychippus isonesus secundus Osborn, type, Amer. Mus. 14179. 1, 



Humerus, 3, tibia, a, anterior, b, external view. 



" " " " " 4. M. isonesus quartus Osborn, type, Am. Mus. 14184. Anterior view of 



tibia. (Reversed in drawing). 



" " " " " 2, 5. M. isonesus quintus Osborn, type, Am. Mus. 14185. 2, Humerus, 



5, tibia, a, anterior, b, external view. 



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