182 ^-^^ DESCENT Ot" MAN. 



fication, it seems that we have at last gained a clew to the 

 source whence the vertebrata were derived.* We should 

 then be justified in believing that at an extremely remote 

 period a group of animals existed resembling in many 

 respects the larvae of our present Ascidians, which diverged 

 into two great branches the one retrograding in develop- 

 ment and producing the present class of Ascidians, the 

 other rising to the crown and summit of the animal king- 

 dom by giving birth to the vertebrata. 



We have thus far endeavored rudely to trace the geneal- 

 ogy of the vertebrata by the aid of their mutual affinities. 

 We will now look to man as he exists; and we shall, I think, 

 be able partially to restore the structure of our early pro- 

 genitors, during successive periods, but not in due order of 

 time. This can be effected by means of the rudiments 

 which man still retains, by the characters which occasion- 

 ally make their appearance in him through reversion, and 

 by the aid of the principles of morphology and embryology. 

 The various facts, to which I shall here allude, have been 

 given in the previous chapters. 



The early progenitors of man must have been once cov- 

 ered with hair, both sexes having beards; their ears were 

 probably pointed and capable of movement ; and their 

 bodies were provided with a tail, having the proper muscles. 

 Their limbs and bodies were also acted on by many mus- 

 cles which now only occasionally reappear, but are normally 

 present in the Quadrumana. At this or some earlier period 

 the great artery and nerve of the humerus ran through a 

 supracondyloid foramen. The intestine gave forth a much 

 larger diverticulum or caecum than that now existing. The 

 foot was then prehensile, judging from the condition of the 

 great toe in the foetus; and our progenitors, no doubt, were 

 arboreal in their habits, and frequented some warm, forest- 

 clad land. The males had great canine teeth, which served 



*But I am bound to add that some competent judges dispute this 

 conclusion; for instance, M. Giard, in a series of papers in the 

 " Archives de Zoologie Experimentale," for 1872. Nevertheless, this 

 naturalist remarks, p. 281, '' L'organization de la larve ascidienne en 

 dehors de toute hypothese et de toute theorie, nous montre comment 

 la nature pent produire la disposition fondamentale du type vf. tebre 

 (I'existence d'une corde dorsale) chez un invertebre par la seu'e con- 

 dition vitale de I'adaptation, et cette simple possibilite du p>ssage 

 supprime I'abime entre les deux sous-regnes, encore bien bu'eu ignore 

 par ou le passage s'est fait en realite," 



