304 ANTHROPOID APES. 



may be put, on the same plan with that of other 

 mammals; the occasional reappearance of various 

 structures — for instance, of several distinct muscles, 

 which man does not normally possess, but which are 

 common to the Quadrumana ; and a crowd, of analo- 

 gous facts ; — all point in the plainest manner to the 

 conclusion that man is the co-descendant with the 

 other mammals of a common progenitor." * 



"The most ancient progenitors in the kingdom 

 of the vertebrata," observes the same great English 

 naturalist in another place, " at which we are able 

 to obtain an obscure glance, apparently consisted of 

 a group of marine animals, resembling the larvsB 

 of existing Ascidians. These animals probably gave 

 rise to a group of fishes as lowly organized as the 

 lancelet ; and from these the Ganoids, and other 

 fishes like the Lepidosiren, must have been de- 

 veloped. From such fish a very small advance 

 would carry us on to the amphibians. We have 

 seen that birds and reptiles were once intimately 

 connected together; and the Monotremata now, in 

 a slight degree, connect mammals with reptiles. 

 But no one can at present say by what line of 

 descent the three higher and related classes, namely, 

 mammals, birds, and reptiles, were derived from 

 either of the two lower vertebrate classes, namely, 

 amphibians and fishes. In the class of mammals, 

 the steps are not difficult to conceive which led from 

 the ancient Monotremata to the ancient Marsupials ; 

 and from these to the early progenitors of the 

 placental mammals. We may thus ascend to the 



Darwin's Descent of Man, 1st edit., vol. ii. p. 385. 



