84 THE ENTOMOLOGIST. 



eighth abdominal segment. Just before the posterior margin of 

 the opening reaches here, the ninth and tenth segments are seen 

 within the larva skin to be actively directing the extremity of the 

 pupa dorsaily, and pushing the dorsal part of the roll of larva 

 skin backwards. The pupal extremity thus curls forwards, with 

 a definite step at each vermicular movement, and, before one 

 quite expects it, it appears through the opening dorsaily. It is 

 not the stiff spike one knows in the mature pupa, but contorts 

 itself as actively as the same segments in the most lively Tortrix 

 or Tinea larva, bending not only at the incisions of segments, 

 but in their length. It then stretches and pushes over the side 

 of the larva skin, and reaches the silken carpet. The remainder 

 of the pupa then leaves the larval skin, and pushes it away. 



The larva of galactodactylas has many stiff hairs, and it 

 seemed that the larva, when inverted, maintained its j)osition, 

 and did not swing free, like a Vanessa, by the pressure of the 

 hairs of the last segments posterior to the prolegs against the 

 surface of suspension. This does not explain how the problem 

 is met in the smoother larvse, if, indeed, these do assume so 

 difficult a jjosition. Agdistis, for instance, takes usually a 

 vertical attitude, with head downwards. 



The larval skin accumulates round the eighth abdominal seg- 

 ment and ventrally remains there, whilst dorsaily it is pushed 

 further back by the ninth and tenth segments, which, as I have 

 noted above, thus escape from the dorsal slit in the larval skin, 

 and find the silken pad to which the cremastral hooks on ten 

 become fixed. What prevents the skin going further back 

 ventrally, and what supports the pupa after the cremaster is 

 withdrawn from the larval skin ? The same answer solves these 

 two questions. The cremastral hooks on the under side of eighth 

 (abdominal) segment, which, like the anal ones, are already 

 stiff and chitinised, stand out like a brush and form an obstacle 

 to the further progress of the larval skin backwards. One 

 specimen which I arrested, at the critical moment when the 

 cremaster was freed, had these hooks in a sort of pocket of the 

 larval skin, of which the anterior lip was the roll of larval skin, 

 the posterior the margin of the slit in the larval skin, and in some 

 degree the roll of dorsal skin behind this and the inside of the 

 bases of the anal prolegs of the larva. 



I have remarked that the last segments are very soft and 

 mobile, and the under surface of eighth being sharply curved and 

 made very convex by the dorsal movements of ninth and tenth, 

 will spread the cremastral hooks of its armature in a radiating 

 manner, so that taken together they form a sort of a knob in the 

 pocket of larva skin, and hold the pupa firmly and safely. It is 

 evident that when the end of the pupa seizes the pad of silk, 

 and the pupa then straightens itself, the radiating hooks will 

 fall together and easily free themselves from the pocket. There 



