EELATION OF MAN TO THE TERTIARY MAMMALIA. 269 



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

 the forthcoming quarto 

 reports of the Hayden and 

 Wheeler U.S. Geological, 

 etc., surveys of the Terri- 

 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 



Fia. 45. — Cori/phodon elephantopus, anterior 

 foot from above, one third natural size. From 

 Lower Eocene of New Mexico. The cuneiform 

 (C«) is injured. (Original.) 



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- 

 fers in the points of dif- 

 ference which are com- 

 mon to all Mammalia. 

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



Fio. 46. — Posterior foot of Coryphodon elephan- 

 topus. From Lower Eocene of New Mexico. (Orig- 

 inal.) 



