. THE GENUS ACRONYCTA AND ITS ALLIES. 
171 
apart. The white on 3 and 4 has dwindled to a dorsal lozenge 
just including the inner tubercles, there is an indication of a 
similar pale patch, towards the anterior margins of 6, 7, 8, g, 
and 10. II has the white porcellanous look of the hinder 
segments of young aim, and the posterior trapezoidals are 
rather on a sub-segment, with marked lateral bosses. 
In the 2nd skin the markings and colouring remain the 
same, ii being still conspicuous as colourless, wide laterally, 
and flat dorsally, with minute tubercles. As it grows it presents 
a great resemblance to alni at the same age, it sits curled round 
with the head against the side in the same way. The dorsal 
tubercles are prominent, so as to give the same angularity and 
squareness to the dorsal outline. There are two white patches 
between the tubercles on the centre of 3 and 4. 12 and 13 
form a decidedly larger mass than two ordinary segments. 
On the nth segment, the anterior trapezoidals are conjoined 
into a plate or cushion and the posterior on another, which 
stretches across the segment, and two similar plates on each 
side represent the supra- and sub-spiracular tubercles, or at 
least carry their bristles. There is a hair to each tubercle as 
in the previous skin, and no secondary hairs. Some specimens 
carry a yellow patch on the centre of the dorsum of 5-10 ; the 
sub-spiracular tubercles of 3 and 4 are yellow. The post- 
spiracular is large and pale on most segments and carries three 
hairs. The laterak boss of ii deserves closer notice; it con- 
sists of the two plates already mentioned and a third beneath 
them, arranged so as to form a trefoil protuberance, the leaflets 
joining together anteriorily, the upper one carrying the spiracle 
and the supra-spiracular tubercle, the 2nd the post-spiracular 
and sub-spiracular tubercles, and the 3rd the marginal one. 
This is a more puzzling and elaborate arrangement than exists 
in any other species, and continues in some degree through the 
next two or three moults. The lateral tubercle of 13 seems to 
be a sub- and post-spiracular fused. 
In the 3rd skin, 6-10 mm. in length, the favourite attitude 
is that of a pot-hook with head against gth segment, like 
strigosa, without the extra bend of alni. Unlike strigosa and 
psi, etc., it broadens out and flattens from 10 to 13, but from 
5 to 10 the tubercles still give an angularity to the outline 
viewed laterally. The trapezoidals and supra-spiracular 
tubercles are black, each with one black hair. The sub- 
spiracular is pale as also the post-spiracular, which is very 
large, both of these carry several long white hairs. The large 
