ANIMAL LOCOMOTION. 87 



It is worthy of remark tliat in Equus and Dipus we have highly 

 specialized forms of foot-strnctures ; aud in Primates, while the 

 foot on the whole is generalized, the astragalus sends a remark- 

 ably inward directed and obliquely placed neck in a direction 

 which would render it difficult for the cuboid bone to reach it. 



It must be acknowledged as a great difficulty how an inter- 

 mediate group arose in which a simple form of tarsal disposition 

 is retained. While from facts presented by Professor Flower it 

 would be natural to assume that Orycteropus might move the 

 foot in a manner different from Myrmecophaga, nothing can be 

 urged why Hyena should differ from Canis, or Dasyprocta aud 

 Capromys from Arctorays. 



An examination of the carpus showed less disposition for the 

 outer elements of the series to be placed inward than is the case 

 in the tarsus. The cuneiform bone, which corresponds in position 

 to the calcaneum, and the unciform, which corresponds to the 

 cuboid bone, remain in all forms of the manus in constant relation 

 to the rest of the carpus. But the entire lateral division of the 

 carpus exerts a disposition to displace the os magnus inward and 

 upward in a manner which is strikingly exhibited in the follow- 

 ing scheme. 



The OS magnum articulates with the scaphoid bone in 

 Coelogenys, Tapirus, 



Rhinoceros, Sus, 



Dicotyles, Clirysochloris. 



Hippopotamus, 

 That is to say, the os magnum, in addition to articulating with 

 its own axially disposed element, the lunare, secures an articula- 

 tion with the scaphoid bone. 



The OS magnum articulates with the lunare only in , 



Dasyprocta, Elephas (variable with 



Capromys, trapezoidal-lunare), 



Erethizon, Tapirus, 



Hyrax, Manatus, 



Hystrix, Orycteropus, 



Arctomys, Myrmecophaga, 



Uintatherium, Myogale. 



In summarizing these results, it may be said that the fact of the 

 outer border of the pes coming to the ground in the first stage of 



