OBJECTIONS TO THE THEORY 311 



with respect to "the last touches of perfection in the 

 mimicry"'; as in the case given by Mr. Wallace, of a 

 walking-stick insect (Ceroxylus laceratus), which resem- 

 bles "a stick grown over by a creeping moss or junger- 

 mannia." So close was this resemblance that a native 

 Dyak maintained that the foliaceous excrescences were 

 really moss. Insects are preyed on by birds and other 

 enemies, whose sight is probably sharper than ours, and 

 every grade in resemblance which aided an insect to 

 escape notice or detection would teod toward its pres- 

 ervation; and the more perfect the resemblance so much 

 the better for the insect. Considering the nature of the 

 differences between the species in the group which in- 

 cludes the above Ceroxylus, there is nothing improbable 

 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 several species are the most apt to vary, while the 

 generic characters, or those common to all the species, 

 are the most constant. 



The Greenland whale is one of the most wonderful 

 animals in the world, and the baleen, or whale-bone, one 

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

 on each side of the upper jaw, of about 800 plates or 

 laminae, which stand close together transversely to the 

 longer axis of the mouth. Within the main row there 

 are some subsidiary 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 animals subsist. The middle 



