PROTECTIVE EESEMBLANCES IN LEPIDOPTERA 29 



common for the crown to be deeply notched, thus 

 producing two humps which make a very natural end 

 to the apparent twig. In the caterpillar of the Small 

 Emerald Moth {Hemithea thymiaria) there are two 

 additional humps on the body-ring (prothorax) behind 

 the head, and the latter is bent forwards and inwards, 

 so that the end of the caterpillar is made up of four 

 blunt projections, forming perhaps 

 the most suggestive of all the resem- 

 blances to the end of a twig. 



In the larva of the Early Thorn 

 Moth {Selenia illunaria) the head 

 and first two body-rings are bent 

 backwards at right angles to the rest 

 of the body. The supporting thread 

 of silk passes between the third pair 

 of true legs, which a,re borne by a 

 high ridge projecting from the angle. 

 The ridge continues the line of the 

 body, and is coloured like it, while 

 the head and first rings are of a 

 different colour. The whole effect is exceedingly un- 

 caterpillar-like, and very suggestive of some eccentric 

 vegetable growth (see fig. 4). 



In order that the resemblance may be complete, it 

 is essential that the caterpillar should appear to grow 

 out of the branch in a natural manner. The two 

 pairs of claspers assist in producing this effect, for 

 they partially encircle the branch, and appear to be 

 3 



Fig. 4.— The larva of 

 Early Thorn Moth 

 {Selenia illunaria) ; 

 adult ; natural size. 



