52 



How did such a curious malformation come to occur ? And what 

 may we learn from it? 



A first and more simple conclusion it points to is one we might 

 have arrived at before, and in fact knew, even if we did not definitely 

 state it, and that is, that the male appendages strictly are those 

 existing interiorly in this specimen, and that those that it presents 

 externally are the normal elements of the ninth and tenth segments, 

 modified, the ninth to support the true appendages, but not really 

 part of them, the tenth also modified to form the uncus, an adjuvant 

 to the appendages proper, but again not part of them. They may 

 be called ancillary appendages, in a similar sense only to that in 

 which the term might be applied to the antennae and intermediate 

 legs in Odynerus spi/iipes, or to the dilated tarsal joints of some 

 Dytiscids. 



How did these parts come to occupy such an interior situation ? 

 All the authorities I have been able to consult agree that the clasps 

 are derived from the ectoderm of the ninth abdominal segment, 

 but in none of them do I find such detailed research devoted to 

 them as to the ducts and other unquestionably internal parts, and 

 I have met with no clear account of their first appearance, and the 

 conclusion arrived at seems to have been reached in a rather 

 perfunctory manner. 



The strongest fact in support of the view that they are dermal 

 structures is that they possess hairs (in the Lepidoptera). It is, • 

 however, to be doubted whether this can be regarded as at all con- 

 clusive ; whatever their real origin, they have been external (in the 

 imago) for so long that one would expect them to have acquired 

 some dermal characters, whatever their true origin may be. 



In this specimen there can be no doubt that there is retained by 

 these parts a situation that is normal to them at some earlier stage 

 in their development. They come from the interior, and at pupation 

 assume an external position by the extrusion of the two rounded 

 eminences characteristic of the male pupa. These pupal covers of 

 the mature structures are here internal. 



It seems impossible to avoid this conclusion, a conclusion that 

 postulates a different history of the development of these organs from 

 that at present accepted, accepted, however, on an apparently in- 

 adequate basis of observed facts. 



These organs, then, are at one period of their development 

 internal structures, and they can be so, it would seem, in one of two 

 ways. One of these would make their origin similar to that of the 

 wings, an invagination of the derma of the ninth abdominal segment 

 at an early period, remaining until the period of pupation as an 

 " imaginal disc," then to come to the surface again. 



If this were the case, one would expect to find instances of the 

 wings not again reaching the surface, but being developed in the 

 thoracic interior. I am not aware that any of the frequent cases of 

 moths with one wing wanting have ever been found to have it in the 



