598 Notes in 1887 upon lepidopterous larve, ce. 
ducted with anything like the same energy by a true 
Geometer. When disturbed the larve contract into a 
curious irregular zigzag, in one plane, and remain 
motionless for some considerable time. This attitude is 
not unlike that assumed by many young Geometers 
under similar circumstances. I have also noticed the 
same movements and the same attitude in the young 
Euchdia glyphica during the past summer. A careful 
drawing was made of the young larva of H. mi, after 
having been fed for a few days in the 1st stage, and is 
represented in fig. 8. The absence of the 1st and 2nd 
pairs of claspers is distinct, and the whole appearance 
strongly suggests that of aGeometer. The chief bristles 
and tubercles are very clearly seen, and possess a very 
typical arrangement. 
15. THE DETERMINATION OF SEX IN CERTAIN LIVING 
LEPIDOPTEROUS LARVH.—It has long been known that the 
essential reproductive glands are to some extent diffe- 
rentiated in the larval state. The changes undergone 
in this and the succeeding stages are beautifully repre- 
sented in the plates of Herold’s work on the development 
of Pieris brassice (‘Entwickelungsgeschichte der Schmet- 
terlinge,’ 1815). 
The testes and ovaries occupy similar positions rela- 
tively to the segments of the larva, being found beneath 
the skin of the 5th abdominal segment, as paired 
bodies, placed one on each side of the dorsal vessel, 
just above the digestive tract. The testes form two 
distinct reniform or lobate masses, while the ovaries 
have the form of two relatively minute and somewhat 
twisted tubes. In addition to this, the testes are gene- 
rally highly coloured, being very commonly yellow or 
brown, and sometimes even bright red. Hence it follows 
that these organs can be easily seen beneath the skin of 
all fairly transparent larve, such as most of the Micro- 
Lepidoptera. By careful examination they can often be 
made out in moderately transparent Geometer, Noctua, 
and also other larve. The ovaries, on the other hand, 
can only be doubtfully seen in the most transparent 
larve with the aid of alens. Knowing the anatomical 
position and structure of the organs, I felt sure that the 
yellow bodies I had so often seen in the larve of Tor- 
trices must be the testes; but, before calling attention 
