ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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but may bo due to the differences in temperature to which the individuals 
are exposed in the two climates. 
Male Genitalia of Yphthima.* — Messrs. H. J. Elwes and J. Edwards 
have made a revision of this genus of Lepidoptera by the aid of the 
characters afforded by the male genitalia. Little use of these parts has 
been made by any other lepidopterists than Messrs. Godman and Salvin, 
though the experience we have proves that they present great stability 
of form in the groups which we are accustomed to regard as species ; 
they remove the individual judgment as a factor in doubtful cases, and 
they afford a final appeal in cases of difference. The parts to be pre- 
served are the tegumen, the two clasps, and the single chitinous piece 
which is known as the oedeagus. Mr. Salvin, by means of a combination 
of cardboard and cover-glass, produces a cell for balsam-mounting which 
possesses all the advantages of the ordinary cell, and which can be 
pinned in the cabinet. Although the authors believe that the use of 
these characters will be greatly extended, they see objections in the 
necessity of exercising patience and dexterity in making the prepara- 
tions, and in the “mutilation” of specimens. On the whole, the appli- 
cation of the genitalia test shows that the species of these Insects are 
more numerous and the species less liable to vary than has been generally 
supposed. 
Metamorphosis of Lepidoptera. j — Prof. E. Bugnion has a notice of 
the researches of M. J. Gonin. His chief results appear to be : — 
(1) Part of the appendages of the head and thorax of the perfect 
insect arise, during the larval stage, from an evagination of a fold of the 
hypodermis which has previously been invaginated into the body. 
(2) These appendages soon receive tracheae and nerves which bud 
off from neighbouring trunks ; M. Gonin shows, contrary to the opinion 
of Landois and Verson, that the tracheae are not the cause either of the 
folding or of the expansion of the walls of the wing, but that these 
phenomena are rather due to the proliferation of hypodermic cells and 
to the resulting increase in surface. 
(3) The buds for the wings are developed in the earliest larval 
stage, and may be seen in suitable sections as soon as the egg is extruded. 
The buds for the other organs are not visible till after the third or 
penultimate eedysis of the caterpillar. 
(4) The legs of the larva only contain the extremities of the homo- 
logous organs of the adult ; the amputation of a leg of a larva destroys, 
therefore, only the extremity of a leg of an imago. 
(5) The buds of the antennae, jaws, and labial palps are folded on 
themselves at the base of the corresponding parts of the larva. 
(6) The number of twelve thoracic discs, which was considered as 
typical by Weismann, is not found in Lepidoptera, while in the 
Hymenoptera the dorsal discs of the prothorax are wanting. 
(7) As the germs of Lepidoptera are not discoid in form, they are 
better called imaginal buds or folds. 
(8) These buds serve sometimes for the formation of new organs, 
* Trans. Entomol. Soc. Lond., 1893, pp. 1-54 (3 pis.), 
f Mittheil. Schweiz. Entomol. Ges., viii. (1893) pp. 403-7. 
1893. Z 
