THE GENUS AORONYCTA AND ITS ALLIES. 
173 
fuscous and dotted closely with extremely small yellowish or 
greenish-white points, each carrying a minute hair ; these dots 
are aggregated into rows, where they partially coalesce and 
form paler longitudinal lines, viz., in line with anterior trape- 
zoidals, below the posterior trapezoidals, in line with supra- 
spiracular and sub-spiracular tubercles ; the post-spiracular 
rises a little above level of spiracle. The larva is thus 
covered with an extremely fine pubescence — length 15-19 mm. 
In the last (6th) skin the length is 20-35 mm. The larva 
differs from the previous skin chiefly in a duller and more 
uniform coloration giving a generally hoary appearance. 
Before it is full grown the great size of the head is remarkable, 
and remains so to some extent when it is full grown. The 
escutcheon on nth segment preserves to some extent the pale 
character of this segment in the young larva. The head is 
black, with two lavender stripes placed vertically on either 
side, the centre ones joining above the clypeus, which is also 
lavender, with the labrum, the palpi, and a patch below the 
ocelli. I have a long description of the larva, but with what I 
have said under skin 5 and its being really well known, this 
may be properly omitted. 
In the matter of spinning, megacephala closely resembles psi 
and tridens. Its proper procedure is probably to get behind a 
piece of rotten wood or bark, but it will excavate a hole into 
rotten wood or pith of elder, etc., as well as tridens or alni, and 
is more loth than either of them to go into earth, rubbish, or 
sawdust, and will wander about disconsolately for days before 
submitting to do so. The cocoon it makes is much like that 
of tridens, but with rather more silk and of a more robust 
character ; but it makes only the cocoon, no outer defence, 
like alni or leporina. 
The pupa (PI. III., fig. 5, 56, 5c) in colour, texture, general 
aspect and outline closely resembles psi and tridens, length 
20-22 mm., width 5|— 6 mm., therefore larger and more robust 
than they. The wing portion is cylindrical, the free abdominal 
tapering. Down the back is a rather darker shade. Two fine 
brown hairs exist at the base of each antennae, but though 
larger than in tridens, would certainly not be seen unless 
specially looked for. The angularity of the free segments at 
the incisions is more decided than in tridens. 
The fixed abdominal segments 5, 6, 7 and 8 besides being 
pitted minutely have more markedly in some specimens than 
others, certain depressions, that look at first as though the 
