382 THE ORIGIN OF SPECIES 



blances. Lamarck first called attention to this subject, and he has 

 been ably followed by Macleay and others. The resemblances in 

 the shape of the body and in the fin-like anterior limbs between 

 dugongs and whales, and between these two orders of mammals 

 and fishes, are analogical. So is the resemblance between a mouse 

 and a shrew-mouse (Sorex), which belong to different orders; 

 and the still closer resemblance, insisted on by Mr. Mivart, be- 

 tween the mouse and a small marsupial animal (Antechinus) of 

 Australia. These latter resemblances may be accounted for, as it 

 seems to me, by adaptation for similarly active movements through 

 thickets and herbage, together with concealment from enemies. 



Among insects there are innumerable similar instances; thus 

 Linnaeus, misled by external appearances, actually classed an 

 homopterous insect as a moth. We see something of the same kind 

 even with our domestic varieties, as in the strikingly similar shape 

 of the body in the improved breeds of the Chinese and common 

 pig, which are descended from distinct species; and in the simi- 

 larly thickened stems of the common and specifically distinct 

 Swedish turnip. The resemblance between the greyhound and the 

 race-horse is hardly more fanciful than the analogies which have 

 been drawn by some authors between widely different animals. 



On the view of characters being of real importance for classi- 

 fication, only in so far as they reveal descent, we can clearly under- 

 stand why analogical or adaptive characters, although of the ut- 

 most importance to the welfare of the being, are almost valueless 

 to the systematist. For animals, belonging to two most distinct 

 lines of descent, may have become adapted to similar conditions, 

 and thus have assumed a close external resemblance; but such 

 resemblances will not reveal — will rather tend to conceal their 

 blood-relationship. We can thus also understand the apparent 

 paradox, that the very same characters are analogical when one 

 group is compared with another, but give true affinities when the 

 members of the same group are compared together: thus, the 

 shape of the body and fin-like limbs are only analogical when 

 whales are compared with fishes, being adaptations in both classes 

 for swimming through the water; but between the several mem- 

 bers of the whale family, the shape of the body and the fin-like 

 limbs offer characters exhibiting true affinity; for as these parts 

 are so nearly similar throughout the whole family, we cannot 

 doubt that they have been inherited from a common ancestor. So 

 it is with fishes. 



Numerous cases could be given of striking resemblances in 

 quite distinct beings between single parts of organs, which have 



