pupa with functionally active mandibles. 263 
jaws can be worked than by fluid pressure acting in 
some way on their bases or on their contents, either by 
the contraction and expansion of this area, or of fluid 
acting through the mouth and imprisoned by the pres- 
sure of this area against the chitinous ring. 
Walter (Jenaische Zeitschrift, 1885, p. 760) describes 
certain chitinous ridges as representing the jaws in the 
imago of Micropteryx, partly led thereto by the analogy 
of Hriocephala, and partly, no doubt, by the fact that a 
chitinous ridge in this situation is a jaw, if it is any true 
mouth-part ; and I am not prepared to say that he is 
in error in doing so; whilst my own observations were 
not made with sufficient accuracy, owing, I think, as 
much to my own inexperience in such matters as to the 
inherent difficulties attending them; but it appeared 
to me that these chitinous ridges were rather borders 
to the pale soft area already referred to, and formed a 
margin into which the hard ring carrying the jaws was 
fitted. 
The whole question, however, of how these jaws are 
worked will form an interesting research for some micro- 
anatomist. I fear my own training leaves me unequal 
to carrying the matter much farther. I am, however, 
thoroughly satisfied on two points—Ilst, that there are 
no muscles attached to these jaws; 2nd, that there are 
no imaginal jaws within them, whose movements compel 
those of the pupal ones. 
If we are to accept, as I suppose we must, these 
creatures as veritable Lepidoptera, then the whole 
character of the pupa, as especially displayed in the 
emergence of the moth and the character of the moth 
itself at that epoch, are only slightly less remarkable 
than is the possession of active jaws. 
The pupal case, except portions of the head, and the 
wing and leg cases, is very soft and delicate, and 
shrivels up as the moth emerges, much as a larval skin 
does; no joint even of the limbs seems quite soldered, 
but those of the segmental incisions are quite as freely 
movable as ina larva, and the intersegmental membrane 
is, notably on the prothorax, stretched by the moth 
inside pressing forwards, just as a larval skin is; and 
similarly the first indication that emergence has made 
any progress is the appearance of some shrivelled empty 
pupal skin at the anal extremity, and the shrivelling up 
TRANS. ENT. SOC, LOND. 1893.—PART Ill. (SEPT.) T 
