On the Osteology of the Hyopotamidas. 171 



digits. The relation between the carpal and tarsal bones and the 

 remaining two middle metacarpals and metatarsals remains just 

 the same as it was in the tetradactyle ancestor. The remaining 

 digits do not exhibit any modification by which they receive 

 more ample support from the carpal and tarsal bones, by taking 

 the place formerly occupied by the now reduced and lost lateral 

 digits. This mode of reduction I call inaclaptive, or reduction in 

 which inheritance is stronger than modification. As an instance of 

 this inadaptive mode of reduction, I may point out the foot of Atm- 

 phtherium and Xiphodon. The annexed diagram clearly illustrates 



this mode of reduction. The fourth digit does not even take the 

 whole of the unciform, and a part of this bone is still occupied 

 by the useless rudiment of the fifth digit ; the third has not ex- 

 tended over the whole os magnum ; and the useless rudiment 

 of the second digit occupies its typical place on the trapezoid, 



