CENOZOIC TIME — TERTIARY. 



911 



of the leg from /to t. Moreover, the upper ends of the tibia and fibula are 

 soldered into one bone. In many species of Artiodactyls the soldering is so 

 complete that no suture is left to indicate it. This addition to the length 

 of the legs, by putting the foot vertical on its toes and elongating the foot 



1538. 



Aetiodactyl Ungulate. — Fig. 1538, Poebrotherium laWatum, restoration (x^'j); a, b, same, feet, less 



reduced. Scott. 



(especially the metatarsal and metacarpal bones), was of great advantage to 

 the running animal ; for it served, as also in the Horse, to give a propor- 

 tional increase of speed, other things equal. 



The Fauna comprised also several Insectivores ; also Beavers, among 

 Rodents, as the Pakeocastor Nebrascensis Leidy, besides other species. 



The Protoceras beds of Wortman, making the upper part of the White 

 Eiver group, are characterized by various Artiodactyls related to the Camel, 

 Deer, and Hog, and the remarkable Protoceras of Marsh, which has long 

 canines and horn-cores, the fore feet 4-toed, while the hind feet are 2-toed ; 

 also others related to the Tapir and Rhinoceros, and various Carnivores and 

 other species. 



The John Day beds of Oregon are characterized by the genera Miohippus, 

 DiceixttJierium, TJiinohyus, Poebrotherium, Eporeodon, Elotheriiim, various 

 Rodents and Carnivores of the genera Cynodon, Temnocyon, Dinictis, and 

 others. 



In the Deep River beds of the Upper Miocene occur the first known of 

 Mastodons {M. p)roavus of Cope), Rhinoceroses of the genus Ap)lielops, several 

 genera of the Horse type, Miohippus, DesmaUppus, Anchitherium, Proto- 

 hipjnis. 



The Loup Fork beds are characterized by species of Procamelus, and the 

 related Protolabis, Protohippus, Aphelops, Mastodon (M. mirificus of Leidy), 

 and by Deer of the genera Blastomeryx and Cosoryx, together with Carni- 

 vores of the genera Canis and Machcerodus. 



