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, 11 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 lateral boss of 11 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 



