■iio * [October, 



OBSEEVATIONS ON C0CCID2E (No. 2). 

 BY ALBERT C. F. MORGAN, F.L.S. 



In my last paper (p. 42 ante) I offered some introductory remarks 

 upon the different genera of Diaspina, and upon the formations of the 

 scales, both male and female, on which those genera depend. I did 

 not mention several genera which appear to have been established 

 upon other grounds by different authors, but it may be well now to 

 glance through these. The genus Leucaspis (including only two 

 species) has all the external characters, as regards scale and exuviae, 

 of Mytilaspis, and this is confirmed by Signoret (Ess. s. 1. Coch., p. 

 144). It is only after microscopical examination that differences are 

 found in the arrangement of certain glandular organs and caudal 

 appendages in the female ; but whilst these afford excellent characters 

 for specific determination, it seems scarcely desirable that they should 

 subserve generic purposes, as in that case, the uniformity of the rule 

 on which the genera of this sub-family {Diaspina) has been estab- 

 lished, becomes imperfect. The same remark applies to the genus 

 Poliaspis, established by Maskell (Acct. Is. Z. Cocc, p. 56), and which 

 includes only one species. Of this genus, Comstock (Ag. U. S., 2nd Rep., 

 p. 126) writes : "I am far from feeling sure that the genus will prove 

 to be a natural one." The genus Targionia, established by Signoret, 

 included only one species, and was abandoned by Comstock (pp. cit., 

 p. 82) because it was founded upon that species showing a ventral 

 scale ; but this is not uncommon with many species of Aspidioti. The 

 genus Asterodiaspis, including again only one species, was also aban- 

 doned by Prof. Comstock, who says (I. c, p. 30) : "A more careful 

 study of this species has convinced me that it does not belong to the 

 DiaspinaB^ The genus Aonidia was established by Targioni-Tozzetti, 

 to include the one species which he considered to be identical with 

 the Coccus aonidum of Linnaeus. Signoret mentions the genus and 

 the species, but re-names the latter Aonidia lauri ; but it seems to me 

 that this genus can hardly be maintained, for the characteristics of it, 

 as mentioned by Dr. Signoret (op. cit., p. 147) are common to many 

 other genera. He says (I. c.) " l'insecte a l'etat parfait serait done 

 plus petit que primitivement, ce qui est un fait extraordinaire." But 

 I have found this a very common feature of many of the Diaspina. 

 The second skin is also mentioned by Signoret as being only separable 

 from the first after maceration in water ; but I think it will be found 

 that this is necessary in many instances. 



I think I have now cited all the genera of Diaspina which have 

 been established by different authors, and, as far as those which I have 



