THE ORIGIN OF SPECIES 



away. Then there are numerous cases of stick and leaf insects (Figure 

 91), which, so long as they do not move, look like parts of the plants on 

 which they are normally found. Many moths (Figure 92) have a close 

 resemblance, when at rest, to the bark of the trees upon which they are 

 usually found. In a few instances, resemblances to the environment are 

 actively acquired. Thus the masking crabs, of which Loxorhynchus cris- 

 patus (Figure 93) is a good example, actually "plant" upon themselves 

 algae, hydroids, sponges, and other sessile organisms from their environ- 

 ment. If a masking crab is moved from its original locale, it will seek, in 

 its new environment, an area with the same kinds of organisms which it is 

 carrying. If no such area is available, the crab will remove its riders and 



II 



Figure 91. Resemblances of Animals to Leaves. 1, Platax vespertilio. 2, Timandra 

 amata. 3, Kallima paralekta. 4, Systella rafflesii. 5, Ctjcloptera sp. 6, Monocirrhus poly- 

 acanthus. 7, Rhampholeon boulengeri. 8, Smerinthus occUatus. 9, Polychrus marmo- 

 ratus. 10, Bufo tijphonius. 11, Miniodes ornata. 12, PhyUiuni crurifolium. 13, Choera- 

 dodis rhomhoidea. Numbers 2, 3, 4, 5, 8, 11, 12 and 13 are insects; 1 and 6 are fish; 

 10 is an amphibian; and 7 and 9 are reptiles. (From Cott, "Adaptive Coloration in 

 Animals," Methuen & Co., Ltd., London, 1940. ) 



242 



