CENOZOIC TIME — TERTIARY. 



905 



1524-1527. 



1527 



1525 



1526 



1524 



tlieriuni and Stylinodon of Marsh, from the Bridger beds. Figs. 1519-1521 

 are of Tillotherium fodiens; 1522, of T. latidens; and 1523, ot Anchip.podus 

 from Marsh. 



Examples of later specializations are here illustrated (Figs. 1524-1527), in 

 Tapir-like species ^ of the genera Eohippus and Oroliippus of Marsh, the former 

 from the Wasatch beds, and the latter from the Bridger. In EoM-ppus the 

 fore feet (Fig. 1524) have all 

 the five toes represented, but the 

 first toe is already reduced to a 

 *' splint-bone " in its metacarpal, 

 while the hind feet (Fig. 1525) 

 have lost wholly the first toe 

 with the metatarsal above, and 

 the fifth toe is reduced to a splint- 

 bone. In the later Orohippus 

 the first toe of the fore foot with 

 its metacarpal (Fig. 1526) is 

 wholly wanting, and the first 

 and fifth of the hind foot (Fig. 

 1527) are wanting. Fig. 1526 

 affords an illustration also of the 

 change in the relative positions 

 of the car pals of most Mammals 

 (and also usually of the tarsals) from that of vertical series (the prototypic 

 position) to that in which the bones alternate with one another (Fig. 1526), 

 so as to give the joint greater strength and safety. This change, with others 

 of like import, began even in the Eocene. In addition, the metacarpals are 

 much elongated. 



1528. 



Fig. 1524, Eohippus pernLx, left fore foot ; 1525, id. left hind 

 foot ; 1526, Orohippus agilis, fore foot ; 1527, id. hind 

 foot (all X I). Marsh. 



Tapirus Indicus, the modern Malayan Tapir. 



1 On account of the frequent references in the remarks on Tertiary Mammals to the 

 Tapir, a figure of a modern species is here introduced. It shows its general form, short 

 legs, and elongate nose. 



