462 ^lE- HUGH SCOTT OX AN 



insect lies extended. Under the microscope there can be seen in the walls a structure 

 consistiuo-, not of interlacing threads, but of branches anastomosing in all directions 

 (PL 34. fig. 0, a). They are colourless, transparent, and glassy in appearance, and very 

 minute, their thickness being less than half that of the white threads covering the insect's 

 bodv. The skeleton that they form is best seen in the margin of the cup ; in the rest of 

 the walls it is covered with opaque material (PL 34. fig. 6, b) of brownish and yellowish 

 colour, with felted masses of threads, and with some of the larger white threads so 

 characteristic of the insect. In the denser portions the substance of the ovisac has to 

 .some extent a radiate arrangement ; irregular thicker parts run from the .base towards 

 the margin of the cup, and alternate with thinner and more translucent portions. Tlie 

 ovisac, like the white threads, will not dissolve in cold chloroform, xylol, or ether. The 

 mode of its formation cannot be made out in the preserved material. 



Such is the structure in the great majority of specimens. But in a very few of the 

 dried specimens the ovisac has proved to be completely closed except for an opening on the 

 somewhat spout-like prolongation corresponding to the tail of the insect. As mentioned 

 above, in the open ciips there is a depression in the wall to accommodate the tail, and in 

 one case this depression was just arched over, so that it formed a round hole (PL 34. 

 fio-. 5, a). This is probably an intermediate stage between tlie open depression and the 

 closed prolongation containing the tail. It appears as if, at a later stage in the life- 

 history than that attained by most of these specimens, more secretory material is added 

 to the open cup, so that the latter l^ecomes a closed structure, completely shutting in the 

 female, as is the case in the allied genus Asterolecaninm *. One of tliese closed structures 

 was empty, the other contained a much shrivelled female. This latter one bore on its 

 outer surface a number of the white threads, but they formed a mass much smaller than 

 that of the threads covering the females seated in open cups. 



In several of the specimens preserved in formalin, each of the tubercles of the dorsal 

 longitudinal rows bears a small plate or flake of glass-like secretion, insoluble in cold wax- 

 dissolving reagents. Each of these flakes is attached at its central part to the surface of 

 the tubercle, and has in its peripheral portions exact impressions of the pairs of pore- 

 plates of the circumjacent integument. Through somp of these impressions rise the 

 threads secreted from the pore-plates beneath. The whole appearance suggests that the 

 secretion has been poured out from glands on the tubercle, has flovved in all directions 

 from this central point, surrounding the bases of the threads emerging from the pits, and 

 has hardened into the transparent flake, receiving in the process impressions of the pits 

 and pore-plates of the integument. It is possible that, by further excretion, the separate 

 flakes on the tubercles may grow in extent till they unite and form a single complete 

 covering to the dorsal surface, continuous at the sides with the margins of the cup-like 

 ovisac, thereby transforming the latter into a closed structure. But there is no proof 

 that such is the case. 



, Hale Fupariiim (PL 34. fig. 8). — The puparia are attached to the woody stems of the 

 Selianthemum. Each is about If mm. long, much smaller than the ovisac, elongate- 



* Ncw.'^tead, ' ilonograph of British Coccid.T,' vol. ii. p. 1.50. 



