8 MR. H. J. ELWES ON THE GENUS PARNassius. (Jan. 19, 
ample, in another 100 pairs may be insufficient to illustrate all the 
points in the history of a species. 
With respect to the development and function of the pouch in this 
genus, which appears to me interesting not only to lepidopterists but 
to all pissisnis of Biology, I must here acknowledge the assistance I 
have received from Mr. afin Thomson, of the Society’ s Gardens—who 
undertook and carried out in a most painstaking manner the ecbser- 
vations on living insects, of which an account is given below— 
and especially to Mr. Salvin and to Prof. Howes, of the Biological 
Laboratory, South Kensington, who undertook the difficult an 
delicate task of dissecting and examining the specimens preserved 
by Mr. Thomson at the Gandena 
And though much remains to be done before we can say that we 
fully understand this intricate question, yet a distinct advance has 
been made on our previous knowledge, and certain facts which were 
previously doubtful or obscure have been proved. The first writer 
who seems to have paid much attention to this organ was Von Siebold, 
who published in the ‘ Zeitung fiir wissenschaftliche Zoologie,’ 1850, 
iii. pp. 54—61, and reprinted in the ‘Stettiner entomologische Zeitung’ 
1851, pp. 176-185, a long and most valuable paper on the subject, 
a précis of which, from an English translation kindly lent me by Mr. 
Gosse, I am here able to give :— 
The first part is historical, and shows that though Linnzeus, 
Latreille, and Schiffer had mentioned the existence of the pouch and 
described its form more or less incompletely in P. apollo and P. mne- 
mosyne, Do one had carried these observations any further. Ochsen- 
heimen accepts its existence in the female as a generic character of 
Doritis, and Boisduval separates Doritis apollinus from Parnassius 
because it has no pouch. 
Siebold doubted whether the organ really formed part of the 
body, as he found that he could easily separate it in P. mnemosyne, 
and, with more difficulty, in P. apollo, as in this species it is glued 
more strongly by its base to the underside of the abdomen. 
He then suggests that it originates during copulation, in these 
words :—‘‘ Probably from the male or female individual, at the anal 
region there is secreted a clammy coagulable fluid, poured forth 
during the close association of the genital organ of the male with 
that of the female, which, by coagulating and hardening, produces a 
firm and long-enduring union of both sexes. After the end of the 
copulative act, and after the complete severance of the sexes, there 
remains this coagulated substance as a sort of cast or impress of the 
hinder parts of the male in the vicinity of the sexual orifice of the 
female, a witness of the accomplished coitus.’ He then states that 
virgin females fresh from the pupa have no pouch, and says that 
Hoger was mistaken when he suggested that the pouch was after- 
wards protruded from the body for the purpose of oviposition. He 
then goes on to state that a chemical examination of the substance of 
the pouch by Dr. Baumert showed that it had no affinity with the 
chitinous substance of the body of the insect, which was insoluble 
when treated with caustic alkali; whereas the pouch of both P. apollo 
