ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
29 
of tho embryo (ectohlastic), but in Eliyncbota and LibelliilidaD the embry- 
onic rudiment is invaginated into the yolk, and the embryo with the 
ventral amnion is separated from the ectoptygma by a layer of yolk 
(entoblastic), while in Lepidoptera an intermediate mode of development 
occurs. Emery protests against the conclusions suggested by Graber’s 
application of the above differences to the classification of Insects, and 
insists on the necessity for more extended embryological investiga- 
tions. 
Morphology of Lepidoptera.* — Mr. W. Hatchett Jackson, in his 
j)aper under this title, deals with two points in the anatomy of the 
Macrolepidoptera — the external anatomical indications of sex in the 
chrysalis, and the mode in which the azygous portion of the oviduct 
with its accessory organ developes in the female. It seems to have 
esc iped the notice of all observers that it is perfectly easy to determine 
the sex of a given chrysalis; the distinctive characters are to be found 
in the sternal region of the ninth abdominal segment in the male, and 
in the corresponding region of both the eighth and ninth abdominal 
somites in the females. The male has a fine short line corresponding 
to the aperture of the ductus ejaculatorius, and this line has two small 
oval lips. The female has typically two fine linear depressions which 
correspond to tlie paired vesicles invaginated from the larval hypo- 
dermis, and to the apertures of the bursa copulatrix and oviduct in the 
adult. 
One of the greatest peculiarities of the Lepidoptera is the existence, 
in connection with the female reproductive organs, of two separate ex- 
ternal apertures, that of the bursa copulatrix, and that of the oviduct. 
Mr. Jackson has made an investigation of the development of these parts 
in Vanessa lo, and comes to the conclusion that the aperture of the 
bursa copulatrix belongs to the eighth somite, and is, strictly speaking, 
the homologue of the single genital aperture of other Insecta; the 
Lepidoptera have really two post-genital somites intervening between 
the genital aperture and the anus, and the oviducal aperture is an 
acquired peculiarity. While these statements are true of most Lepi- 
d,oi)tera, it is recognized that variations may occur, as in Nematois 
metallicus, described by Cholodkowsky. 
Three distinct stages appear to be indicated in the phylogenetic 
liistory of the female reproductive organs. In the first stage paired 
larval oviducts opened at the posterior border of the seventh abdominal 
somite, as in existing Ephemeridse. If accessory organs were present 
they opened independently on the two succeeding somites. In the 
second stage a short vagina or azygous oviduct, derived from the hypo- 
dermis of the eighth somite, made its appearance. The bursa copulatrix 
and receptaculum seminis opened close behind its aperture or into it 
on its dorsal aspect, while the sebaceous glands retained a se2)arate 
aperture. Very similar arrangements obtain in many living Orthoptera. 
Finally, in the third stage, the sebaceous glands open into a continua- 
tion of the vagina which possesses a second terminal aperture — a 
disposition of the j>arts which is specialized in the Lepidoptera. 
* Zool. Anzeig., xii. (1889) pp. 622-6. 
