1887] The Perissodactyla. 1067 
inthe genera Palzotherium and Paloplotherium. Thence it ex- 
tends to the very summit of the Miocene, and may even occur 
in the European Pliocene (Protohippus). Its members exhibit 
considerable range of variation in the details of the teeth and 
feet, but no striking break of family importance occurs. The 
most noteworthy interruption is that which is found between the 
Paleotherinze and Hippotheriinz, where there is a change in the 
form of the proximal extremity of the humerus from a tapiroid 
toa horse-like form, and a modification of similar significance in 
the molar teeth, by the addition of a deposit of cementum. 
Fic. 32. Paleotherium crassum Cuv., superior molars from below, three-quarters 
natural size; from Gaudry. From the Upper Eocene of Paris. 
The characters of the genera are as follows: 
L Paleotheriine, Bicipital groove of humerus simple; teeth without cementum. 
a. One or more internal tubercles of superior molars distinct. 
External V’s of superior molars not well E exter- 
nally ;.... ...Anchilophus. 
External V's separated by a vertical rib; intermediate "tubercles 
not Connecting fore and aft ;......cccsecesseenscsscersersanconnernet’” 
al V’s separated ; TORSIE tubercles extended lore and : 
aft;. „Anchippus. 
..s.rsos 
Whe Win E R died E E PS Gob EEA O E ITA TO E a a a eate 
Pa loplotherium. 
: Ti io molars with two V’s only; lateral toes large; ..------ serere 
i erior Tas with distinct internal tubercles; incisors not 
m 
PEERI O T aa TA 
ine, ntaa l groove of humerus " aale 
rs 
8g valleys. jon Se i tubercles saul at and aft; inciso 
cupped.) i 
