PLATE 15. 



UPPER TEETH OF MERYCHIPPUS FROM NORTHEASTERN COLORADO, THREE SPECIES FROM THE MIDDLE 



MIOCENE OF COLORADO. 



COMPARISON OF EARLY AND LATE STAGES OF WEAR. 



All figures natural size. 



Pawnee Creek, northeastern Col. Middle Miocene 1. Merychippus sphenodus Cope, cotype, Am. Mus. 8281 (reversed 



in drawing). This "cotype" belongs to a distinct species, 

 more primitive than the type. 



" " " " " " 2. M. sphenodus Cope, type, Am. Mus. 8281. Teeth little worn 



(partly reversed in drawing). 



" " " " " " 3. M. sphenodus Cope, referred specimen, Am. Mus. 9400. Teeth 



well worn. 



" " " " " " 4. M. campestris Gidley, type Am. Mus. 9096. Teeth little worn. 



" " " " " " 5. M. campestris Gidley, referred specimen, Am. Mus. 9459 (re- 



versed in drawing). Teeth much worn. 



" " " " " " 6. M. proparmdus Osborn, type, Am. Mus. 9394. Teeth much 



worn. 



" " " " " " 7. M. proparvulvs Osborn, paratype, Am. Mus. 9398. Teeth 



much worn. 



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