194 
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 cons<£t\ lion 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 e Nat. Hist, of Mammals,’ by C. L. 
Martin, 1841, p. 415. Also, Isid. Geoffroy on the American monkeys 
and other kinds, 4 Hist. Nat. Gen.’ yol. ii. 1859, p. 216, 243. Esch- 
richt, ibid, s. 46, 55, 61. Owen, 4 Anat. of Vertebrates,’ vol. iii. p. 619. 
AVallace, 4 Contributions to the Theory of Natural Selection,’ 1870, p. 
344. 
9 4 Origin of Species,’ 5th edit. 1869, p. 194. 4 The Variation of 
Animals and Plants under Domestication,’ yol. ii. 1868, p. 348. 
