1062 The Perissodactyla. [Dee, 
with diastemata, is Lambdotherium. The same type, without 
incisors, gives us the Asiatic Nestoritherium. The development — 
Fic. 27. Paleosyops major Leidy, superior molar teeth, one-half natural pre 
after Cope. From the Bridger Eocene of Wyom 
of cross-crests is accomplished, as in other families, by the com 
pression and fusion of the intermediate and internal tubercles. 
When the external Y’s are little pronounced, we have Pachyno- 
lophus; when they are well developed and the anterior innet 
tubercle remains distinct, we have the genus Chalicotherium 
These relations are probably phylogenetic, and may be repte 
sented as follows: 
Limnohyus. Lambdotherium. 
Palæosyops. Cale 
Epihippus. Leurocephalus. Pachynolophus. 
Ectocium. 
