] 82 THE DESCENT OF MAN. 



tication, it seems that we have at last gained a clew to tho 

 source whence the vertebrata were derived.* We should 

 then be justified in believing that at an extremely remote 

 peiiud a group of animals existed resembling in many 

 respects the larvae of our present Asciclians, which diverged 

 into two great branches the one retrograding in develop- 

 ment and producing the present class of Ascidians, tho 

 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 toman 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 Quadrnmana. At this or some earlier period 

 the great, artery and nerve of the humerus ran through a 

 supracondyloi-i foramen. The intestine gavo forth a much 

 larger divertieulum or ccecum than that now existing. Tba 

 foot was then prehensile, judging from the condition of rbo 

 great toe in the fcevus; and our progenitors, no doubt, wore' 

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

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



* But I am bound to acid chat some competent judges dispute this 

 conclusion; for instance, M. Giard, m a series of papers -n the 

 " Archives de Zooiogie Experimentale." f or 1372. Nevertheless, this 

 naturalist remarks, p 281, >: L'organizntnn 'Je la larve ascidierne en 

 dehors de toute bypotiiese et de loiite theorie, nous niomre comment 

 la n m: u re pent pro.iuire la disposition fondamentale du type veltebre 

 (1'existenre d'une corde doi>ale) chex nn invertebre par la seule con- 

 dition viiale de 1'adaptation, :>t cette simple possibilite <iu passage 

 supprinie J'abime entre les deux sous-regues, encore bien qu'en ignore 

 jwr ou le passage s'est fait ea realite." 



