262 



MR. B. F. CUMMINGS ON 



proved by specimens in Stage III. about to moult with the imago 

 beneath visible through the old skin. A comparison for example 

 between text-figs. 14 and 1 shows the extent of the change. 



In P. brachyrrhynchus, P. oxyrrhynchus, as well as in P. spinu- 

 losa, the chsetotaxy of the head and thorax in the larval 

 stages is almost identical with that of the adult. This prohably 

 holds for all the Anoplura, On the abdomen the larval chseto- 

 taxy differs from stage to stage, and it is a matter of particular 

 interest to trace the sequence in which the hairs develop. Thus 

 in the abdomen of P. oxyrrhynchus and P. spinulosa there is a 

 tendency for the hairs to appear first at the end of the abdomen, 

 and to develop subsequently in later stages further forward. 

 For example, in Stage I., there are no hairs on the pleura? 

 except in the last segment, while the only hairs on the ventral 

 surface appear first on the last segment. 



The sexes of the larva? are indistinguishable — at all events in 

 external form. In the last stage the male copulatory apparatus 

 is in some specimens visible in the imago beneath. 



Text-fig. 10 is a representation of the egg, found in some 

 numbers in the tube with both species ; I am unable to say to 

 which it belongs. 



POLYPLAX OXYRRHYNCHUS. 



Stage I. (Text-fig. 11.) — The head is short and broad, and 

 there are no sclerites on the abdomen. The sexes are indistin- 

 guishable, the abdomen in all specimens ending in a cone. The 

 insect is very soft and delicate, and requires to be dehydrated 

 very slowly in carefully graduated alcohols before clearing, if 

 complete and instantaneous shrivelling is to be avoided. In 

 parts, however, the cuticle is harder and more perfectly developed, 

 e. (/., the mouth-parts (to enable the young larva to pierce and 



Stage I. — Measurements {millimetre scale). 



