June, 1897.] Webster : On Protective Mimicry. 75 



but the object of all of these efforts would be the protection of life, by es- 

 caping capture and securing food to sustain that life, and the most suc- 

 cessful would be the most apt to survive. 



But have we not had, during all of this time, a consciousness of pos- 

 sible destruction and volition in the efforts put forth to get out of the way 

 of an enemy in pursuit ? Do not these, in fact, coexist with animation 

 itself; and does not their presence really afford natural selection the 

 primary foundation with which to begin the development of certain 

 characteristics, and perfect such to an extent necessary to the life of an 

 organism ? 



Another kind of phenomena, commonly termed feigning death, also 

 comes within the scope of this paper, and includes such species as, when 

 they are alarmed, either fall to the ground or assume certain rigid po- 

 sitions while attached to plants, or both, so as to appear either dead or 

 like some lifeless object. Many insects, when disturbed, will draw up 

 their legs and falling down remain perfectly still and rigid until the 

 supposed enemy has passed on. Very many of our beetles do this, and 

 because of our common opossum Didelphys virginiana, taking a similar 

 course in its attempts to escape death, the action has been vulgarly 

 termed "playing possum." Species belonging to the Coleopterous 

 genera Chlamys and Exema, however, are shaped and colored so as to 

 almost exactly represent the excreta of caterpillars, and when feeding, 

 if disturbed, will drop to the ground if not caught by the leaves of the 

 plant upon which they are feeding, and as they lay perfectly still, may 

 be unrecognized by even fairly good entomologists. But, even the pe- 

 culiar form and color of these insects would fall far short of protecting 

 them while feeding, as their position at that time is so entirely different 

 from that under which the excreta of caterpillars is usually observed ; 

 but, when they loose their hold, and drop to the upper surface of a 

 lower leaf and either remain there or roll off and fall upon the ground, 

 the deception is complete. 



The resemblance of the larvae of Geometridge, to small twigs of trees 

 and shrubs is everywhere observed, and as universally excites feelings of 

 delight and surprise. When disturbed, the caterpillars assume a rigid 

 position, more or less transverse to the limb upon which they are lo- 

 cated, so that their position, together with the peculiar form and color 

 of their bodies, render them not easily detected. In some species, the 

 form of the body is such as to closely resemble a dead twig, even to the 

 buds thereon. In this case it requires the assumption of the peculiar 

 and rigid position, in order to complete the deception so far as it is 



