THE CHRYSALIS. 41 



the antennae and partially overlapped by them, 

 is a smooth crescent-shaped belt, which corre- 

 sponds closely in position with the curving row of 

 simple ocelli in the head of the caterpillar, where 

 it is generally marked by a distinct impression ; 

 it also lies across the middle of the convexity 

 which marks the position of the compound eye of 

 the inclosed butterfly ; the convex case of the 

 rest of the eye is rough and coarse like the chrys- 

 alis skin generally, but this curved ribbon is 

 smooth and thin, and regularly embossed, each 

 gentle elevation apparently cor- 

 responding to the centre of a 

 facet of a compound eye [Fig. 

 53 J. Now it has been suggested 

 that this belt is a window FIG. 53.- Head of 



chrysalis of Euphoeades 



through which the prisoner may Troiius; side view to 



show the eye; X 2. 



look abroad ; what end this 

 would serve is not explained ; nor have the 

 structure, form, and position of the belt been 

 taken into consideration, or, so far as I am aware, 

 even stated. Two things, however, may be re- 

 marked : first, that no underlying structure has 

 been found related to it alone ; second, that as an 

 external covering of an eye its structure is mid- 

 way between that of the caterpillar and the per- 

 fect insect. May it not be a relic of the past, the 

 external sign of what once was ? And are we to 

 look upon this as one hint that the archaic but- 



