EELATION" OF MAN TO THE TERTIARY MAMMALIA. 



269 



Fig. 45. — Caryphodon elepJiantopiLS^ anterior 

 foot from above, one third natural size. From 

 Lower Eocene of New Mexico. The cuneiform 

 {Cu) is injured. (Original.) 



recent explorations in the West, and the results are embraced in 



the forthcoming quarto 



reports of the Hayden and z^^^fc^^'^K^S'c 



Wheeler U. S. Geological, Cu 



etc., surveys of the Terri- ^'n- 



tories. An abstract of 



some of these is given in 



the present essay. 



The primary forms of 

 the Mammalia repose in 

 great measure on the struc- 

 ture of the feet. Those of 

 the teeth are also very sig- 

 nificant, but present a 

 greater number of varia- 

 tions among animals other- 

 wise nearly related. The 

 osteology of the feet of re- 

 cent land mammals falls into several categories. These may be 



called the plantigrade, 

 many-toed type ; the car- 

 nivorous type ; the horse 

 type, and the ruminant 

 (e. g., ox) type. The 

 lower vertebrates, as sala- 

 manders, lizards, etc., dis- 

 play the simplest form of 

 feet, having usually five 

 toes, with numerous sepa- 

 rate bones of the palm 

 and the sole, which they 

 apply to the ground in 

 progression. The many- 

 toed or multidigitate 

 type of mammalian foot 

 most nearly resembles 

 this condition, but dif- 



FiG. 46.— Posterior foot of CorypTiodon elephan- fers in the points of dif- 

 topus. From Lower Eocene of New Mexico. (Orig- f p^'ence which are Com- 

 mon to all Mammalia. 

 In the hind foot a succession of forms leads from this general- 



