FISH. 



RABBIT. 



MAN. 



EXPLANATION OF PLATE. 



The Figures marked A represent thi 

 corresponding stages of the development o 

 the embryo of a fish, a rabbit, and a man 

 The gill-slits are drawn in thick lines 



In all three instances the arteries sup 

 plying the gill-slits are after the patten 

 shown in Figure D. 



The Figures marked B show a furthe 

 stage in the evolution of the th: 



Th 



gill-slit 

 developed 01 

 apparatus ; 1 

 and of them 

 Both of the; 

 the fish, hnvi 

 The Flu 



nf the fish 



2 lines of a water-breathing 

 the gill-slits of the rabbit 

 re undergoing modification. 

 mbryoes, as well as that of 

 movable tail. 



? marked C show that, 

 whereas the gill-slits are permanent in the 

 water-breathing fish, they have disappeared, 



as altogether useless, in the rabbit and the 



The Figure marked E shows, by the 

 darker shading, the permanent arrangement 

 of the arteries of a mammal. The lighter 

 shading indicates the useless portions that 

 are generally absorbed ; but they some- 

 times remain as rudiments. 



The Figures marked F show some of 

 the muscles of the human ear. Those which 

 are attached to the scalp, and which, in dis- 

 tant ancestors, moved the ear as a whole, 

 forwards, backwards, or upwards, can be 

 thrown into action by few people now living 

 on the earth. Those muscles which are 

 situated on the organ itself, and which 

 formerly regulated its shape, are now 

 absolutely powerless and useless. 



