6 Transactions. — Zoology. 



at least nearer to the ventral surface of the segment than to 

 the dorsal ; that several species of Diaspids are without them 

 altogether, and yet form scales or puparia ; and that some- 

 what similar organs are found in certain insects close to the 

 oral setae: he concludes therefore that they are not "spin- 

 nerets," but " salivary glands." I am not prepared to deny 

 altogether the force of these reasons. Yet it should be noted 

 that at least these little organs, whilst they differ to some 

 extent from the dorsal " spinnerets " of Diaspids, resemble 

 very closely the dorsal organs which have been by common 

 consent considered as " spinnerets " in the other groups. On 

 the dorsal surface of, say, Asjndiotus, the tubular organs 

 noticeable are different from those in the "groups;" and in 

 several Lecanid or Coccid insects there are also more or less 

 tubular organs. But there are also in these nearly always a 

 number of circular ones which are quite similar to the "grouped 

 orifices" of Asioidiotus. For example, they are very numerous 

 in G celo stoma ; and again in Planchonia, where their double 

 form is merely a variation. Close examination of a " group of 

 orifices" in a Diaspid will show that they are " multilocular" — - 

 that is, composed of several openings all enclosed in a.n outer 

 circle; and Targioni, in plate ii., fig. 23, of his " Studii," 

 correctly delineates them as such. In this character they 

 exactly resemble the dorsal organs of Coelostoma : it would 

 seem therefore probable that they fulfil the same function. 

 The figure-of-eight orifices of Planchonia exhibit only one small 

 circle within each outer one : this appears to be an unimportant 

 variation : but undoubtedly these double organs lie at the base 

 of the double long tubes forming the fringe of the insect, and 

 must be taken as the orifices of excretion of the tubes. On the 

 whole, therefore, it would seem to be clear that the "grouped 

 orifices" of a Diaspid are similar to the " spinnerets " of a 

 Coccid or a Monophlebid ; and as, so far, no actual jproof has 

 been adduced that these organs are not engaged in the excre- 

 tion of some substance, I have thought it best to retain the 

 word "spinnerets" for the Diaspidinas.* 



It may happen that I may be unable to continue in future 

 years these "Notes on Coccids : " I therefore take this 

 opportunity of giving here a short list of the works which will 

 probably be most useful to anybody who may take up the 

 study of these insects. 



* I find that "grouped orifices" are present, close to the thoracic 

 spiracles, in Asindiotus aurantii (very small), Diaspis rosea (very largo 

 and conspicuous), Mytilaspis pomoruvi, Myt. leptospermi, Myt. inter- 

 media, Myt. metroaideri. In all probability they occur in every species of 

 the Diaspidinis. 



