THE SUTD^, OR PIGS. 141 



that the Peccary (Dicotyles), by the simplification of 

 its limbs which is advantageous for running has 

 advanced farther than Sus ; it is, in fact, a better 

 runner than the Pig, and we are fully justified in 

 supposing that both animals will make still further 

 progress in this direction. They are, without doubt, 

 swifter runners than were their ancestors with their 

 less reduced feet, and a further advantageous re- 

 duction will depend only upon circumstances. The 

 inward disposition towards this exists, but I must 

 beg the reader not to confound the simple word ' dis- 

 position' with the dangerous word 'tendency,' the 

 play-wcrd of philosophers and one apt to lead over 

 to the idea of purpose. If, after many thousands 

 of years, the foot of the American Peccary and the 

 European Sus should have lost every vestige of its 

 second and fifth toes, this would be a perfectly in- 

 telligible, nay, a most obvious case of hornceogenetic 

 convergence. If, however, our Pig and Peccary 

 should no longer exist for the zoologists of the 

 future, they would most probably regard the anti- 

 cipated and distinctly two-toed feet of both animals 

 as having been inherited. 



This consideration may now lead us to the ques- 

 tion as to the primary forms of our living Suidte. 



The genus Sus is found only in the Old World, even 

 14 



