1 94 THE DESCENT OF MAN. Part I. 



of the hair on the limbs, and the course of the medullary- 

 arteries. 8 



It must not be supposed that the resemblances be- 

 tween man and certain apes in the above and many 

 other points — such as in having a naked forehead, 

 long tresses on the head, &c. — are all necessarily the 

 result of unbroken inheritance from a common pro- 

 genitor thus characterised, or of subsequent reversion. 

 Many of these resemblances are more probably due 

 to analogous variation, which follows, as I have else- 

 where attempted to shew, 9 from co-descended organisms 

 having a similar constitution and having been acted 

 on by similar causes inducing variability. With re- 

 spect to the similar direction of the hair on the fore- 

 arms of man and certain monkeys, as this character is 

 common to almost all the anthropomorphous apes, it 

 may probably be attributed to inheritance ; but not 

 certainly so, as some very distinct American monkeys 

 are thus characterised. The same remark is applicable 

 to the tailless condition of man ; for the tail is absent 

 in all the anthropomorphous apes. Nevertheless this 

 character cannot with certainty be attributed to inheri- 

 tance, as the tail, though not absent, is rudimentary 

 in several other Old World and in some New World 

 species, and is quite absent in several species belonging 

 to the allied group of Lemurs. 



Although, as we have now seen, man has no just right 

 to form a separate Order for his own reception, he may 



8 On the hair in Hylobates, see ' Nat. Hist, of Mammals,' by C. L. 

 Martin, 1841, p. 415. Also, Isid. Geoffroy on the American monkeys 

 and other kinds, ' Hist. Nat. Gen.' vol. ii. 1859, p. 216, 243. Esch- 

 richt, ibid, s. 46, 55, 61. Owen, ' Anat. of Vertebrates,' vol. iii. p. 619. 

 Wallace, ' Contributions to the Theory of Natural Selection,' 1870, p. 

 344. 



9 'Origin of Species,' 5th edit. 1869, p. 194. 'The Variation of 

 Animals and Plants under Domestication,' vol. ii. 1868, p. 348. 



