186 THE CANADIAN KNTOMOLOGIST. 



for long were considered as the dorsal and ventral portions of this 

 segment, prove on examination of pupal stages to be but secondary 

 processes. The true segment wall remains mostly membraneous, and is 

 usually concealed within the xii segment. Sometimes, however, the anal 

 cone projects, and in such cases the secondary processes are usually 

 absent, and either the dorsal portion (Heliothis, Catocala), or the ventral 

 (Hadena, Nonagria) is more strongly chitinized. The Unacs usually has 

 the form of a single ventrally-inclined hook, but may be bifid or even 

 replaced by several processes or hooks. The Scaphium shows a similar 

 degree of variation, and is often lacking in Rhopalocera, Noduidce, etc. 



The Valves are enormously developed lateral appendages, which are 

 always hinged to the postsegmental margin of the xii segment. Usually 

 symmetrical, they show in several instances (Nisoniades, Pterophoridae) 

 marked asymmetry, and are furnished on their inner concave side with all 

 manner of hooks and bristles. They originate at a late larval period in the 

 so-called genital pouch, an ektodermal invagination of the xii ventral mem- 

 brane. At the bottom of this pouch two conical mounds undergo division, 

 forming two lateral warts, the embryonic Valves, and two centrally placed 

 ones, which afterwards unite to form the embryonic Penis. 



During the pupation stage, owing to the disintegration of the genital 

 pouch, the Valves come to lie on the surface, while the Penis remains at 

 the base of a small secondary depression, the .commencement of the 

 so-called Penis pouch (Penistasche). The remaining development takes 

 place during the pupal period. The Penis pouch, which is possibly 

 identical with the Penis sheath of Poljanec, possesses generally, as seen 

 from behind, a funnel-shaped appearance, narrowing to a fine tube, which 

 enters the abdomen for a considerable distance. The narrowing may be 

 gradual, but in most instances the transition is sudden, and at the point 

 where the pouch enters the body a so called Ringwall (Penis-funnel 

 of Jordan) arises, a hollow cone-like structure, either strongly chitinized 

 all round, thus forming a Ping, or else chitinized only ventrally, giving the 

 appearance of a groove (Sella of Stichel). The outer wall may show a 

 considerable armature of hooks, etc., which in some cases becomes quite 

 complicated, leading Poljanec into the error of supposing that " inner 

 valves ^^ existed. ( Pygaera pigra, Psodos coracina). 



Closely fitted, into the Penis pouch we find the Penis proper ; the 

 proximal portion is merely membranaceous, but the distal end projects 

 out of the Ringwall as a strongly chitinized tube, which is of varying shape 



