Chap. VI.] AFFINITIES AND GENEALOGY. 187 



from co-descended organisms having a similar constitution 

 and having been acted on by similar causes inducing 

 variability. "With respect to the similar direction of the 

 hair on the forearms 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 characterized. 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 inheritance, 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 

 perhaps claim a distinct Sub-order or Family. Prof. Hux- 

 ley, in his last work, 10 divides the Primates into three Sub- 

 orders : namely, the Anthropida3 with man alone, the 

 Simiada) including monkeys of all kinds, and the Lemu- 

 ridae with the diversified genera of lemurs. As far as dif- 

 ferences in certain important points of structure are con- 

 cerned, man may no doubt rightly claim the rank of a 

 Sub-order ; and this rank is too low, if we look chiefly to 

 his mental faculties. Nevertheless, under a genealogical 

 point of view it appears that this rank is too high, and 

 that man ought to form merely a Family, or possibly even 

 only a Sub-family. If we imagine three lines of descent 

 proceeding from a common source, it is quite conceivable 

 that two of them might after the lapse of ages be so 

 slightly changed as still to remain as species of the same 

 genus ; while the third line might become so greatly 

 modified as to deserve to rank as a distinct Sub-family, 



10 ' An Introduction to the Classification of Animals,' 1869, p. 99. 



