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MR. A. T>. TVIICHAEL ON THE LIFE-HISTORIES 



to use the expression " cases " to signify this phase iu the life- 

 history ; it must, however, be understood that each case is only a 

 nymphal skin, but it is a nymphal skin under special conditions. 

 The finely granular marking or wrinkling of the cuticle of the 

 species was very apparent, and when a portion was examined witli 

 a sufficient power this was resolved into the labyrinthine and vermi- 

 form wrinkling of which an illustration is given (PI. XVI. fig. 3). 

 It was also noticeable that the contents of each case were more 

 drawn toward the anterior end than is usual in the nymph during 

 ecdysis. Of course tbe first step was to ascertain that these 

 cases were not simply dead creatures ; for this purpose, in the 

 latter part of May 1885 I isolated three in a separate glass cell, 

 placing them under what experience had taught me would pro- 

 bably be favourable conditions of existence. On the 10th June, 

 1885, three immature Glycii^Jiagus domesticus emerged from these 

 eases. The cases did not split irregularly like an ordinary 

 nymphal skin, but opened by the posterior end of the case, 

 which had been concave, being pushed out so as to become rather 

 convex, and separating from the lateral and ventral portions of 

 the case, while it remained attached to the dorsal ; thus when the 

 creature within had escaped, the posterior end formed a sort of 

 lid attached to the dorsal surface (fig. 4). This I subsequently 

 found was the usual, although not the absolutely invariable, mode 

 of opening. I did not then examine the precise stage that the 

 creatures were in, but I noticed that the cases, although open, did 

 not appear to be entirely empty (I subsequently found that what 

 they contained was a cast skin). 



On the 10th June, 1885, I placed thirteen more cases in a 

 second cell, and submitted them, as 1 had hoped, to conditions 

 similar to the first ; but either from some defect in the arrange- 

 ment of the cell, or from unfavourable weather, these specimens 

 gradually died, so that toward the end of July there were not any 

 alive. On the 30th July, 1885, I again isolated several cases in a 

 separate cell. In a week I found that two of them were open at 

 the posterior end and that there were two nymphs of Glyciphagus 

 domesticus in the cell ; more subsequently emerged from the 

 other cases. I again observed that the cases from which they 

 had come did not appear to be absolutely empty. 1 now took 

 three of the nymphs which had emerged from the cases and 

 placed them in a separate cell ; in about a week they had all 

 become inert ; a few days later an adult female of G. domesticus 



