THE GENUS ACRONYCTA 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 Icporina. 



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 antennas, 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 



