TRIFID^. 221 



extremely suddenly, the three segments 8, 9 and 10 having, 

 very distinctly, the raised hoop-like ridges in question. Dr. 

 Chapman says : " The pupae are black, or nearly so, of a 

 rough, wrinkled, and warty surface ; the free abdominal 

 segments — 9 and 10 — are as wide, or even wider, than those 

 in front of them, the tapering to the tail being done in the 

 remaining fixed segments — 11 to 13 — giving a peculiar 

 squareness to the pupa. There is a double nodule between 

 the eyes ; the posterior margin of each segment, most marked 

 in 9 and 10, has a raised band just like those barrel hoops 

 that are made of a branch split and with the bark left on, 

 whose smooth surface contrasts with the roughness of the 

 rest of the segments. The ^anal armature is a projection 

 with somewhat quadrangular termination, having the points 

 or spines nearly or quite obsolete, but clothed with a brush 

 of stijff brown bristles." The pupa is enclosed in a cocoon 

 of tough whitish silk, fairly copious in amount, but in one 

 simple layer, usually clothed with fragments of grass, twigs, 

 leaves, &c., and often placed against a stump, stone, or post. 

 " The young larva is of typical Acronyda form and colour, 

 in all the five British species being very nearly alike, and 

 very close to the newly hatched larva of 2^si and tridens, but 

 diSering from other groups in having three or more hairs on 

 the anterior trapezoidal tubercles " (raised spots). The eggs 

 are laid in groups, usually in a very regular manner, im- 

 bricated, that is, in regular rows overlapping each other, an 

 arrangement which their flatness permits. 



In the second group — Cus})idia — (cuspis, a spine) the 

 pupa3 are characterised by a peculiar arrangement of long 

 terminal spines. " The pupa is again the most distinctive 

 stage of the group ; it is of the ordinary Nodua, smooth, 

 brown, brittle-looking, semi-transparent, chitinous material ; 

 it tapers regularly from the thickest part of the thorax to 

 the terminal segment, which is somewhat rounded to finish 

 with; and the sculpturing, instead of being raised points, 

 consists of the ordinary minute pits. The anal armature con- 



