ABEKEAXT FORM OF COCCID.E. 457 



The surface of tlie trunk witliia the inner furrows is strongly convex, and at the 

 centre of it is the rostrum, sunk in a depression. The loop of the rostral filaments is 

 long. There is no trace of legs or feet, or of eyes. 



The spiracles (PI. 34. fig. 2, d), as previously mentioned, open, two on either side of the 

 body, into the inner longitudinal furrows. Like the antenme., they are more strongly 

 chitinised and darker in colour than the surrounding integument. Each consists of a 

 shallow circular chamlier, in the external floor of which is the orifice to the exterior, 

 while an opening in the internal floor leads into a tracheal trunk. In connection witli 

 each spiracle is a curiously shaped structure, strongly chitinised, and very conspicuous 

 in specimens that have been emptied of their soft parts by treatment with caustic 

 potash. This structure is adjacent to the side of the stigmatic chamber remote from 

 the lateral margin of the body, and extends forwards and slightly towards the middle 

 line. In transverse sections it appears as a ridge projecting from the cuticle into the 

 interior of the body, and muscles extending from the dorsal surface are attached to it at 

 one point. On the side of the stigmatic chamber nearer the lateral margin of the body 

 is a group of cutaneous glands, which will be spoken of later. 



The ventral surface of the posterior part of the trunk and of the tail shows very 

 distinct division into eight segments (PI. 34. fig. 2). The anal orifice is surrounded by 

 eight setae (PI. 34. fig. 9) rising from a slender chitiuous ring, which has a beaded 

 appearance. Just anterior to this anal ring rise a large and a small pair of setae 

 in close proximity to each other (PL 34. fig. 9), and the integument of the terminal 

 segment in this region bears a number of very minute projections (PI. 34. fig. 9, a). 

 Between the anal lobes is a shorter median lobe (PL 34. fig. 9, b), dorsal to the anus. 

 Each anal lobe (PL 34. fi.g. 9, c) is large ; it bears a long seta at its extremity, and five 

 smaller ones (the arrangement of which is shown in the figure) on its more proximal 

 portions. Every seta rises from a chitinised base, having the form of a cup with a 

 raised and thickened rim. The genital aperture is a somewhat transverse opening in the 

 ventral middle line, in the region of the furrow between the sixth and seventh segments ; 

 the integument immediately surrounding it slu)v\s extremely fine strite radiating from it 

 (PL 34. fig. 9, d). 



Passing now to a considei'ation of the integument and the excretory products of the 

 insect, the most striking feature of all is the very numerous threads secreted by cutaneous 

 glands on the dorsal surface. Those form a dense covering completely concealing not 

 only the body of the female, but also the ovisac in which it lies, and produce the 

 conspicuous wool-like masses on the infected plant. The covering of threads as a whole 

 looks opaque and white : but when highly magnified each thread is seen to be perfectly 

 transparent, colourless, and glass-like ; cylindrical, curving, and sometimes with a 

 certain amount of longitudinal striation in the interior of its substance (PL 34. fig. 7). 

 The threads vary in thickness ; the diameter of cross-section of a rather thick one 

 measured was about 12 ^. Tliese threads are insoluble in cold wax-dissolving reagents. 

 But Dr. Hopkins, to whom I am much indebted for examining them, states that they 

 are formed of a wax freely soluble in hot reagents. It dissolves in boiling absolute 

 alcohol, and separates on cooling into glistening plates of homogeneous appearance. 



65* 



