42 Transactions. — Zoology. 



two dorsal abdomiual lobes, aud the excretion of a drop of 

 honeydew. 



Ctenochiton elaocarpi, like all Lecanids, exhibits at the 

 abdominal extremity a deepish narrow cleft, on the dorsal 

 side of which are two rouudly-triangular protruding lobes. 

 In a specimen of the second female stage it may be seen, 

 mider the microscope, that these lobes lie in a shallow groove 

 formed by the sides of the cleft. At intervals, which may 

 vary in length, the insect protrudes rapidly from beneath 

 the lobes a cylindrical organ (figs, la, lb,), composed of a 

 basal, thickish tube, bearing at its extremity another, similar, 

 but much thinner. The organ being pushed out to its full 

 extent, a minute globule of transparent glutinous fluid appears 

 at its extremity, rapidly expands, something like a soap- 

 bubble, and then suddenly breaks and falls in spray on the 

 leaf. The excreting organ is then rapidly withdrawn. 



I do not entertain much doubt that the process just described 

 is the same used by all the " honeydew "- secreting Coccids. 

 Some of these, like Rhizococcus fossor, Planchonia epacridis, 

 etc., produce much less than others; but even they, I thmk, 

 excrete some. The observation which I have made as above 

 throws a light upon an organ which I noted as occurrmg in 

 the second female stage of Colostoma zalancUcum, in vol. xiv. of 

 the " Transactions," page 227, and in the adult female of the 

 same insect in vol xii., p. 295. I then considered this organ 

 as an oviduct, remarking, however, that I could not see its use 

 in the pupal stage. I never saw it exserted, and was not 

 aware that it ever was so ; but it seems clear to me now that 

 this is an organ similar to the one excretuig honeydew m 

 Ctenochiton elmocarpi, and it probably occurs in at least most 

 of the other Coccids. 



But observation of this organ is extremely difficult, if not 

 in most cases impossible. The best and most careful work 

 on the anatomy of Coccids is that of Professor Targioni- 

 Tozzetti, " Studie sulle Coccineglie " (Milauo, 1867); and there 

 is no mention in it of any such organ. I have carefully, at 

 various times, examined in every way many specimens of 

 different genera, and, with the exception of ddostoma (an 

 exceptionally gigantic species), I have not seen it. 



There is no doubt of the quantity of glutinous matter 

 secreted by Coccids ; but, as observed above, the origin and 

 mode of the excretion have not been noticed before. There 

 does not appear to be any other organ, or any other portion, of 

 the insect's body, producing this secretion ; aud it may well be 

 that the absence of insects feeding on the honeydew may be 

 due to the fact that the excreting organ, instead of being con- 

 stantly protruded like the cornicles of the Aphididae, is only 

 now and then exserted aud then withdrawn. In many genera, 



