210 mSCELLANhlOUS OBJECTIONS TO THE 



respect to '' the last touches of perfection in the mimicry;^' 

 as in the case given by Mr. Wallace, of a walking-stick in- 

 sect (Ceroxylus laceratus), which resembles '^a stick grown 

 over oy a creeping moss or jungermannia." So close was 

 this resemblance, that a native Dyak maintained that the 

 foliaceous excrescences were really moss. Insects are preyed 

 on by birds and ether enemies whose sight is probably 

 sharper than ours, and every grade in resemblance which 

 aided an insect to escape notice or detection, would tend 

 toward its preservation; and the more perfect the resem- 

 blance so much the better for the insect. Considering the 

 nature of the differences between the species in the group 

 which includes the above Ceroxylus, there is nothing im- 

 probable in this insect having varied in the irregularities 

 on its surface, and in these having become more or less 

 green-colored; for in every group the characters which 

 differ in the sevei-al species are the most apt to vary, whiltf 

 the generic characters, or those common to all the species, 

 are the most constant. 



The Greenland whale is one of the most wonderful ani- 

 mals in the world, and the baleen, or whalebone, one of 

 its greatest peculiarities. The baleen consists of a row, on 

 each side of the upper jaw, of about 300 plates or laminae, 

 which stand close together transversely to the longer axis 

 of the mouth. Within the main row there are some subsid- 

 iary rows. The extremities and inner margins of all the 

 plates are frayed into stiff bristles, which clothe the whole 

 gigantic palate, and serve to strain or sift the water, and 

 thus to secure the minute prey on which these great ani- 

 mals subsist. The middle and longest lamina in ^he Green- 

 land whale is ten, twelve, or even fifteen feet in length; 

 but in the different species of Cetaceans there are grada- 

 tions in length; the middle lamina being in one species, 

 according to Scoresby, four feet, in another three, in 

 another eighteen inches, and in the Balasnoptera rostrata 

 only about nine inches in lengtli. The quality of the 

 whalebone also differs in the different species. 



With respect to the baleen, Mr. Mivart remarks that if 

 it ^'had once attained such a size and development as to be 

 at all useful, then its preservation and augmentation within 

 serviceable limits would be promoted by natural selection 



