AND DEVELOPMENT OF COMTS INFELIX. 



243 



I have been unable to settle this question, for in order to do so with any finality it 

 would be necessary to find the creature at the exact time when the change is taking 

 ])lace, and this would entail the examination of a vast number of individuals, and as 

 each examination involves a careful dissection of the small host first, the time required 

 would be considerable. 



It is at this point in its life-history that the creature turns co.npletely roand inside 

 its host. 



iv. Preptqjal Stage. (Plate 11. figs. 10, 17.) 



External form.- — A great change has taken jilace between this and the preceding 

 condition, transforming the larva into the prepupa, or pseudonymph. In this instar 

 the creature is still creamy-white, like the larval forms already described ; it is, however, 

 enclosed in a membrane (PJ. 11. figs. 17, 18, m.), which is probably the remains of the 

 original larval cuticle, and the parasite is now head to tail in the Coccid, instead of 

 head to head as was the case in the larval condition ; its dorsal surface is now closely 

 pressed to the inside of the dorsal surface of its host, whose body it now almost 

 completely fills. The appendages, &c., of the imago body are well defined, though still 

 imperfectly developed in this instar (PI. 11. fig. 17). The head is ditferentiated from the 

 rest of the body, the antenna? and eyes being clearly outlined, Avhile the thoracic region 

 has become more rounded. Tlie rudiments of the legs and wings are folded across the 

 ventral surface, and the segmentation of the abdomen is distinct, so that the creature 

 now exhibits very definitely the form of the perfect insect. Internally, the organs have 

 undergone less change as a result of tl>e histolysis and subsequent regeneration. 

 Packard (44, p. 67) has called this form the semlpupa, and Siebold's term jjseudoni/mph 

 applies to the same instar ; the nymphal form is attained after an ecdysis. 



Tracheal system. — There are in this instar four large stigmita — three situated in the 

 thoracic region and one in the abdominal segments, with six smaller abdominal stigmata 

 which may not he functional, for only traces of the first five can be seen in the imago, 

 and the seventh has entirely disappeared, or has fused with the sixth to form the large 

 functional spiracle which is so conspicuous. 



Situated on each side of the abdomen there are three oval red plates (PI. 11. figs. 10, 

 17, 18, pi.), referred to above. These appear to be connected in some way with the 

 respiratory function of the creature, for they are placed at the base of the large forked 

 tracheal tube, which at that point effects its union with the body, or, in other words, 

 brandies out of the body at that point, to ramify over the membrane which encloses the 

 insect. This membrane has been discussed Avhen tlie preceding instar was being 

 considered. Each of these curious plates is an oblong body applied closely to the outside 

 wall of the abdomen ; under a high power of tlie microscope, one of these plates is 

 seen to contain red globules, of ditferent sizes. It is not easy to determine what the 

 function of these structures can be, but I suggest that thev have some connection with 

 respiration, seeing the radiating tracheal arise at the same place as these anomalous 

 plates. Nothing of this nature has been recorded by Bugnion as occurring in Encyrtvs 

 riiJicoUis, nor can I find elsewhere any statement bearing on these curious structures. 



