THBLAXES PRYOPHILA. 11 



the nervures increasing in number and complication so 

 as almost to suggest a dimorphic character. Repre- 

 sentation of these anomalous forms may be seen in 

 Plate CXVII bis, figs. 7, 8. 



At Montpellier, Thelaxes would seem to show migra- 

 tory habits, like Phylloxera. In summer the partkeno- 

 genetic forms give rise to the agamous generations on 

 Quercus ilex ; and in December these winged individuals 

 give birth to the sexed insects on Quercus pubescens. 

 In the month of November M. Lichtenstein sent me 

 living examples of the oviparous female; each was 

 burdened with a large egg ready for laying. In no case 

 amongst these could I find that the female had more 

 than one egg, yet there appeared to be no difference 

 between the French and English insects. 



In my description of the Genus Callipterus,* notice 

 was taken of Prof. Huxley's memoir on the ' Repro- 

 duction of Aphis. 'f In the former an opinion was stated 

 that the anatomical details ascribed, in that memoir, to 

 Vacima dryophila should be applied to Callipterus 

 quercus. In so expressing myself, it seems to be in- 

 cumbent on me to give reasons, and here I offer the 

 following in substantiation of my views. 



As the true males and females of Siplwnopliora 

 pelargonii, the kind previously used for dissection, 

 could not be detected at that time feeding on the 

 ivy-leaved geranium, Prof. Huxley selected a different 

 species of Aphis for his study, and he found an oak 

 in the Zoological Gardens " infested with multitudes 

 of females, full of ova, and also similar ova adhering 

 to the plant in the axils of the leaves, and more 

 particularly between the outer bracts of the buds." 

 In a note Prof. Huxley says that he does not think 

 that his Aphis is identical with that described by 

 Reaumur as feeding on the oak, or that of Bonnet. 

 " None of the specimens attained the size of theirs, 

 neither do they mention the peculiar dorsal marking 



* ( Mod. Brit. Aphides,' Ray Society, vol. iii, p. 23, 1881. 

 | 'Trans. Lirm. Soc.,' sxii, 1858. 



