170 BRITISH TYROGLYPHID^;. 



instance inside the case, and almost filling its anterior 

 part, but not the legs which were empty, was a proto- 

 plasmic mass ; which had a transparent, colourless, and 

 almost structureless cuticle. This mass had a rounded 

 posterior and a bluntly pointed anterior end ; it was 

 compressed dorso- ventrally, particularly at the posterior 

 margin, and had a more or less plain sulcation round 

 it, as though dividing cephalothorax from abdomen. 

 The mass had the general form of a Hypopus, but 

 there was not any trace of legs, mouth, or other ex- 

 ternal organs. The mass was always motionless, but 

 in one instance I did find a living nymph of G. domes- 

 ticus within the case instead of the inert mass; this 

 nymph was ready to emerge. Almost every case from 

 which the occupant had emerged contained the cast 

 skin of the protoplasmic mass, not showing any trace 

 of legs, mouth, or other external organs. 



In the latter part of 1885 I found in the chaff-house 

 of a farm, both in the dust and chaff and attached to 

 the walls and beams, a number of cases which were 

 more opaque than those of G. domesticus, and were 

 coarsely reticulated instead of having fine labyrinthine 

 markings ; the cases opened differently, the posterior 

 cuticle breaking away from the dorsal and lateral, 

 and remaining attached to the ventral ; so that 

 the posterior end opened downward instead of up- 

 ward, and was more torn ; the hinder part of the 

 dorsal cuticle was usually split along the median line, 

 and the two parts somewhat separated ; one of these 

 cases is drawn (PL VIII, fig. 11); they were after- 

 wards ascertained to be those of Olycyphagus spinipes. 

 I placed some of these cases in a breeding-cell and 

 dissected others ; many contained, not the inert legless 

 mass found in the cases of G. domesticus, but a dis- 

 tinctly formed living Hypopus ; which had not assumed 

 the usual brown chitinous colour and could not be 

 called active ; but still was fully formed, and was pro- 

 vided with legs, although they were short and stumpy ; 

 it could move these limbs freely but could not walk 



