LIFE-HISTORY OF THE FORESY FLY. 10 
then unknown, deposited by the H. cquina, and to secure (as far as 
possible) temperature and circumstances in which this, the first of 
many puparia subsequently experimented on, might be successfully 
developed, he placed the ‘‘egg’”’ (?) in cotton in a bottle safely corked 
up. ‘This he carried by day in his pocket, by night it rested under his 
pillow, and after thus carefully treating it for nearly a month he 
witnessed the development. ‘It was not until the 17th of October 
that I saw the egg open, and I found not an insect which had to grow 
and to undergo transformations ; but a fly in all points similar to that 
by which the egg had been laid, and of which all the parts were of 
equal dimensions with the dimensions of the parts of that by which 
the egg had been produced.* 
“The egg-like body”’ [that is, what proved to be the puparium, 
Ep.] ‘‘when deposited was white, with the exception of the two pro- 
jections at one end, the space between them, and some amount of the 
parts in the vicinity of the notch”’ [for shape, see figure, p. 95, Ep.]; 
‘the envelope hard and firm, and becoming still more so as it changed 
to a brown colour, and thence in about twenty hours to a shining 
black, when it could resist a considerable pressure.’’—Loc. cit. p. 5838. 
The next point in investigation was to trace out the method and 
progress of development of the fly in the puparium, and the first step 
was opening one of the egg-like bodies which had been deposited four 
days later than that from which the H. equina had been seen to 
emerge, and in this, not quite developed (that is, still in pupal state), 
the Forest Fly was observable (see figure 8, p. 95).+ 
The compound eyes (‘ yews a réseau,” or reticulated eyes) were 
already of a reddish colour, and so also were the two external mouth- 
processes, which together form the sheath of the trunk. The rest of 
the pupa was white, excepting some tufts of greyish hairs; and the 
hinder extremity of the pupa, or ‘‘nymph”’ (as it was then called), was 
placed against the notched hinder extremity of the puparium, with 
which, as will be seen on reference to the figures at p. 95, it corresponds 
in the shape of its own notched or heart-shaped end. 
To trace the history in its entirety, Réaumur opened specimens of 
the egg-like puparia at different dates after deposit by the female 
Hippobosca, as of three weeks, ten, five, four, three days, and one day 
* «Mémoires pour servir a histoire des Insectes,’ par M. de Réaumur. Paris, 
mbccuir. Tome sixiéme. (Quatorziéme mémoire, p. 580. 
| This figure is copied from figure 21, plate 48, of Réaumur’s illustrations 
accompanying his paper previously cited, and (as pointed out by the late Professor 
Westwood) it is much to be regretted that this plate is so little known. It contains 
twenty-three figures showing the H. equina in its various conditions, with numerous 
details, presumably from other observations made by M. de Reaumur in the same 
paper, figured with a magnifier of rather more power than half-inch focus, 
