270 BRITISH TYKOGLYPHID^E. 



particularly the tibiae of the fourth pair of legs, increase 

 rapidly in thickness at their distal ends; the whole 

 increase being on the inner sides, so that this projects 

 at its distal end, forming a large curved point; from 

 which the tarsus curves away, completing the distal 

 side of the point. To enable this construction to work 

 the articulation, although close on the outer side, is 

 exceedingly loose on the inner ; the two joints being 

 there attached by a flexible membrane of considerable 

 width, generally bowed outward ; giving great play to 

 the tarsus, probably for clasping purposes. The hairs 

 on the legs differ very little from those of the female, 

 but the third and fourth tarsi of the male have a 

 singular assemblage of small, chitinous, recurved knobs 

 or hooks at their distal ends. 



The Nymph. This is easily known from its simi- 

 larity to the adult, but there are many differences. In 

 the fully-grown nymph the sex is well marked; the 

 bursa copulatrix and other external sexual organs of 

 the female are easily seen ; so that the male and female 

 nymphs are somewhat different, but not so much so as 

 the adults. The fully-grown female nymph is almost 

 white, without the pinkish peripheral colouring of the 

 adult. The legs are about the size of those of the 

 adult ; the abdomen is considerably smaller and more 

 square, its edges are more raised and its central part 

 more depressed than those of the adult. The rough 

 projections around the periphery, instead of being 

 separated by spaces and being absent from the hind 

 margin, form an almost continuous line round the 

 lateral and posterior margins. It is evident that the 

 spikes carried by these projections will thus afford 

 greater protection to the creature during growth at a 

 period of life when the object of the straight hind 

 margin of the female has not arisen. 



The Larva has much the same characters as the 

 nymph, except that it is smaller, more transparent, 

 with the raised edge less strongly marked. It is, of 

 course, hexapod. 



