E\ L. Troxell — Early Pliocene One-Toed Horse. 339 



The antero-orbital pit is of little value as a means of identify- 

 ing the species, the genus, or even the sub-family, for it seems 

 to be a variable feature depending on age or sex. We find 

 both portions well developed in Protohippus and Merychippus 



Fig. 3. 



Fig. 3. Eamus. Side view. One-third natural size. 



Fig. 4. 



fc&> 



B C 



Fig. 4 Permanent Molaks. Two-thirds natural size. 



A, a section l cm from the crown of first true, upper molar. B and C, inner 

 and outer side views of first true, lower molar. D, a section on line, X-Y, 

 of B. 



and the lachrymal pit is even conspicuous in some of the 



Anchitherinae, especially in that aberrant form, Hypohippus. 



On its lower border the ramus has a single large curve in 



front of the angle ; it is like that of Asinus and Ilippanion 



