THE EMERGENCE OF THE CERURAS. 303 
the exposed portion of cocoon, and are practically fixed in that 
position. Then all the cocoons I have examined (thirty or forty) 
have a decidedly thinner place over the front of the head; it is 
larger than the cross section of the pupa; it contains fewer 
chips, and, held against the light, is quite translucent, whilst the 
rest of the cocoon is opaque; this is the portion of cocoon that 
is operated on for emergence. 
I stated (loc. cit.) that the pupe of our Ceruwras were fairly 
rounded in front; in this I was decidedly in error, for vinula has 
nearly as pronounced a keel on the head as C. multiscripta, to 
which I referred. Our “kittens” are much smoother, though 
the same structure is indicated. It was observing this structure 
of vinula that tempted me to try to make further observations. I 
made a detailed description of this portion of the pupa of vinula, 
but I may omit it, as I made no observations that connected any 
habit with any peculiarity of this portion of the pupa. 
The dehiscence of the pupa consists in the thorax splitting 
dorsally, and the division proceeding to either side separating the 
wings from the first three abdominal segments; the antenne 
cases sometimes adhere to the wings, sometimes separate; the leg 
and mouth part coverings form a separate piece, whose apex 
tends to adhere to wings and abdomen. But the head-covering, 
consisting of the ridge (or keel) and hollow on either side of it, 
the eye-covers (including the glazed side portion), the face down 
to a certain incision, and a small portion below which is probably 
the labrum, separates as a distinct portion, and adheres to the 
moth in its proper position, during the whole period of emergence 
and until the head is quite clear of the cocoon, and often even 
after the moth has completely escaped, and is always found out- 
side the cocoon. During this period the rudimentary proboscis 
is very visible as two short white papille, free from any hairs, and 
it is just above the base of these that the softening fluid exudes. 
This fluid is stated to be acid; this I did not test, but I found it 
to be colourless and tasteless, and it evaporated without residue ; 
applied to the material of cocoon it softened it, but not at all 
rapidly. The moth makes many rotatory movements after the 
splitting of the pupa case, no doubt in order to smear this fluid 
over the necessary area of the cocoon, and we here see how little 
further is wanted to reach a habit similar to that of milhauseri, 
especially as the smearing process and delay for softening takes 
a considerable time, probably more than five minutes, possibly 
half an hour. This appears also from the amount of fluff rubbed 
about inside the cocoon in many cases. The moth keeps quite 
dry, and the head-cover is dry outside, but moist within, when 
removed from the newly-emerged moth; its function appears to 
be to protect the front of the moth during the movements of 
smearing, and as a strong medium for applying the final breaking 
2E2 
