1830 .) 
53 
The period of incubation varies, within my observation, from 
fourteen days to six, according to tlie season and the temperature. 
The first eggs I obtained this year were laid on the Gtb of April, and 
batched out on the 20th. In 1877 1 bad eggs in the third week in 
August (the warmest in that year), which hatched in six days. From 
that date the period of incubation gradually increased again to eight 
and eight and a half days. When hatching is imminent, a sudden and 
obvious change comes over the batch of eggs ; the clear yellow colour 
has given place to a darker muddy discolouration, due apparently to 
the development of black warts and spiracles and oblique lines of hairs 
on the body of the larva, and to the complete detachment of the larva 
itself from the enclosing shell. Conspicuous at this stage, on the 
dorsal surface, are four relatively large, somewhat triangularly-shaped, 
blackish spots (warts) seated on the meso- and meta-thorax in a 
quadrate form, and which I call the thoracic square. Within and 
behind these are, on either side the median line, two rows of black 
hairs, appressed, and running obliquely backwards and inwards. In 
front of the thoracic square the head of the larva is noticeable by its 
translucency, while the slightest inclination to one side or other brings 
into view the eye-spots, a group of five reddish points on each side of 
the head. Seen laterally, and perhaps seen more distinctly at a some- 
what earlier stage, because not then liable to be confounded with the 
antennae and palpi, these five eye-spots are grouped, four in a diamond 
whose long axis points obliquely backwards and a little ventrally, whilst 
the fifth, somewhat further away on the ventral side, seems to lie in 
the continuation of a concave anteriorly, crescentic line, formed by 
itself and the two anterior eye-spots of the rhomboid. Assuming the 
head to be composed originally of annular segments, these three eye- 
spots would seem to lie on one, the remaining two on that immediately 
posterior to it. 
The larva now exhibits slow but constantly repeated vermicular 
movements ; the mandibles open and shut ; the tail is generally re- 
curved towards the dorsum. There is, as it were, a crowding forward, 
and an endeavour to advance in the shell by vermicular movements 
chiefly, and in which the legs take no part, while the anal pro-leg is in 
frequent requisition. The large warts of the thoracic square, armed 
with double hairs, are constantly sliding backward and forward along 
the shell. At last, an invisible slit in the longitudinal line of two of 
these warts on one side is effected, revealed at first only by the slow 
erection of a hair which has escaped through it. There is a hump or 
protuberance near the head, seeming to be formed by the prothorax. 
