( xxiv ) 



almost impossible to handle it without producing injury and 

 distortion. Though the markings were there, they were not 

 produced by pigmentation, at least not by formed pigment. 

 The dark markings of the pupal wings were represented by 

 areas that were more transparent than the rest of the wing. 



The fact, he remarked, was curious enough whatever might 

 be its minute anatomy and precise meaning. 



The pigmentation of dark areiis. Dr. Chapman remarked, 

 is usually the latest to develop, and here we have apparently 

 a less development in the dark area than on the pale ; and this 

 may be therefore a reminiscence of an ancestor that possessed 

 these dark markings as an imago. He very much doubted 

 this, however, partly because of the great variability of these 

 dark pupal markings, and partly because there was no 

 question of pigment involved. Specimens of the wings at a 

 later stage, showed the true imaginal markings developed. 

 The white pigment was well developed, while the dark mark- 

 ings were still very transparent, little pigment being yet 

 developed on them. The solidity and firmness of these 

 specimens showed how much later they are than the others. 

 With regai'd to these effects, Dr. Chapman explained them 

 to some extent as analogous to photogi-aphic effects. It was 

 quite possible, he thought, that light and heat caused a 

 differential effect through the different coloured areas of the 

 pupa. 



Another specimen exhibited. Dr. Chapman thought, 

 might throw some light on the question of supernumerary 

 joints and limbs in insects. He had, he said, in tliis con- 

 nection made several hundred experiments upon PortJietria 

 dispar last summer, but of these had as yet only examined 

 about a dozen, one of them being the specimen exhibited. The 

 larval liml) in this case, by some mistake, had not been cleanly 

 amputated, but partially crvished. This was done at the last 

 larval moult, and also probably so immediately after the moult 

 that the parts had not yet fully expanded, still less hardened, re- 

 sulting, as the specimen showed, in their remaining only partially 

 expanded. The result in the imago was a limb in which all the 

 parts were abnormal, even the trochanter, whilst the femur was 

 curiously flattened out triangularly, bearing on one angle an 



