176 fJune, 



for insinuation between the closely Ij'ing coverings of the floret. 

 Such an ovipositor occurs in the genus Oli/pliipteryx, and in many of 

 the ColeophorcB. 



Now, there was one curious point about all these instruments 

 that struck both of us, which was that, freely as they could be pro- 

 truded by the insects themselves, it was impossible to force them out 

 by pressure on the abdomen, as can be done with ordinary ovipositors. 

 It, therefore, seemed natural to conclude that the powerful rods with 

 which they were provided, and which were plainly the agents through 

 which protrusion was effected, would be peculiar to insects having 

 rigid ovipositors ; but happening to examine two or three species, all 

 possessed of telescopic but soft ovipositors, I was surprised to find 

 the rods present. This led to a wider examination, with the result 

 that the rods were always found ; and we must, therefore, conclude 

 that they are present in all Lepidoptera, and are the handles by means 

 of which the ovipositor and the last abdominal segment, or its equi- 

 valent, are worked. In insects with short ovipositors that scarcely 

 reach beyond the abdominal outlet the rods are proportionately small 

 and weak. In an insect, for example, of the size of 'Melanijipe mon- 

 tanata, they are absolutely smaller than in Adela viridella, whilst in 

 so minute a creature as Micropferi/x caltheJIa an ordinary lens would 

 not be powerful enough to demonstrate them. 



Early in the enquiry I came across an unexpected fact. It seems 

 that all male Lepidoptera have eight external segments in the abdomen, 

 but that their number in the female varies. In those with simple 

 ovipositors the number is eight, as in the male, the ovipositor in the 

 one case, and the male appendages in the other, making up the full 

 complement of nine abdominal segments (Latreille's, or the 5th seg- 

 ment, being, to the best of my judgment, thoracic in the Lepidoptera) . 

 But in those with compound or telescopic ovipositors, composed, that 

 is to say, of the ovipositor proper and the sheath, the number of 

 segments is seven, the 8th having been converted into the sheath, and 

 become i]itra-abdominal. As the steps of the operation by which the 

 segment has been gradually changed into a sheath remain stereotyped 

 for us in still existing forms, it may be as well to give them a moment's 

 consideration. In the male insect, and in some of the other sex, the 

 8th is in all respects a typical abdominal segment. It is completely 

 external ; has its surface covered with ordinary scales, in addition to 

 a frill of larger ones along the edge; and, further, consists of two 

 separate plates, a dorsal and a ventral one. It is by no means a com- 

 mon female form, and though it ap])ears to occur pretty widely among 



