1916] Merriam: Relationship of Equus to PlioJiippus 



53] 



18 



Fig. 13. PlioJiippus proversus. n. sp. M 1 or M 2 , type specimen, no. 21330, 

 natural size. Upper Etehegoin, North Coalinga region, California. 



Fig. 14. Pliohippus simplicidens (Cope). Superior premolar?, natural size, 

 Blanco Pliocene, Texas. (After Cope.) The inner single dotted line in recon- 

 struction of the protocone represents the writer 's interpretation of this pillar. 



Fig. 15. Pliohippus cumminsii (Cope). Superior molar, natural size. Blanco 

 Pliocene, Texas. (After Cope.) 



Fig. 16. Equus occidentalis Leidy. P 3 to M 2 , no. 21001, natural size. Pleisto- 

 cene, Eancho La Brea, California. 



Fig. 17. Pliohippus referred to simplicidens (Cope). Lower cheek-tooth 

 series, one-half natural size. Blanco Pliocene, Texas. (After Cope.) 



Fig. 18. Equus occidentalis Leidy. Lower cheek-tooth series, no. 12269, one- 

 half natural size. Pleistocene, Eancho La Brea, California. 



