1888.] 119 



mentioned are concerned, I think it will be convenient, at all events 

 for the present, to consider them insufficiently established. 



I propose now merely to refer to Plate II annexed, which shows 

 the insects removed from their scales, many of which latter were 

 shown on Plate I (ante). All the figures on Plate II are magnified 

 fifty times, in order to show the relative proportions of the insects, 

 and are intended to represent types of the Diaspina. They must not 

 be relied upon when specific determination is required, as the magnifi- 

 cation is too small to allow the engraver to produce with precision 

 minute specific differences, which will be shown on a larger scale in 

 future drawings. 



With the exception of figs. 4, 5, & 9, all represent adult females. 

 Fig. 1 is Diaspis ostreceformis, and fig. 2 is Aspidiotus ostreceformis. 

 The difference in size between these two insects should be observed, 

 although A. ostreceformis is not always quite so large as shown in the 

 figure, which represents an old adult form. These two species (which 

 belong to different genera) were considered as the same species, until 

 Mr. Douglas (Ent. Mo. Mag., xxiii, pp. 239—241) drew attention to 

 their distinction. His opinion was confirmed by Professor Comstock, 

 and subsequently my own observations still further proved the accu- 

 racy of Mr. Douglas' opinion. As this is not the moment for entering 

 more fully into that question, I may perhaps merely mention that the 

 difference of the genera was at once established by the difference in 

 the scale of the male, which is an incidental circumstance in favour of 

 maintaining the character of the scales as the line on which to estab- 

 lish the genera. Pig. 3 represents Mytilaspis pomorum, and this it 

 will be observed is of a different shape to the Diaspis and Aspidiotus, 

 such as one might expect on referring to its scale (see Plate I, fig. 4). 

 This insect is very much smaller in its adult form than in its previous 

 stage, and the second exuviae completely covers the adult form, leaving 

 room for the young to congregate under the shelter of the rejected 

 skin, at the posterior end of their parent, until they move out to find 

 a suitable spot on which to fix themselves by means of their rostral 

 setae, there to remain during the remainder of their lives. Pig. 6 

 represents Aspidiotus rapax, Comstock, found in abundance on 

 camellias in the open air in Portugal, and I presume in other parts of 

 Southern Europe. I am inclined to think that this will prove to be 

 synonymous with A. camellia, Signoret, notwithstanding my previous 

 observations on this question (Ent. Mo. Mag., xxiv, pp. 79 — 82). 

 Pig. 7 is Mytilaspis pandani, which it will be seen is similar in shape 

 to M. pomorum, although a smaller and more delicately formed insect. 



