Entomological Society. 211- 



The Rev. F. W. Hope exhibited a series of drawings of the trans- 

 formations of various Indian Lepidoptera, made by Mr. Ezra Downes. 



The following memoirs were read : — 



" On the Existence of Thoracic Branchiae in the Imago state of the 

 Neuropterous genus Pteronarcys." By George Newport, Esq., Presi- 

 sident E.S. (Annals of Natural History, vol. xiii. p. 21). In refer- 

 ence to this memoir Mr. Westwood stated, that he had detected 

 some thoracic appendages in the genera Ptychopteryx and Heliophi- 

 lus, described and figured in his ' Introduction to the Modern Clas- 

 sification of Insects,' vol. ii. fig. 126, 7. p. 526. note t, and p. 557, 

 which he considered to be analogous to the branchise discovered by 

 Mr. Newport in Pteronarcys. The latter gentleman however objected 

 to this analogy, as the organs in question existed simultaneously with 

 the true spiracles. Mr. E. Doubleday, in reference to a suggestion 

 made by Mr. Newport, stated that he had always noticed that the 

 North American species of ChauUodes are on the wing in rainy 

 evenings. 



" On the proceedings of a species of TromUdium which infested 

 the Plane-trees in the Regent's Park during the past summer." By 

 George Wilson, Esq., M.R.C.S. Communicated with additional 

 notes by A. White, Esq. 



At the beginning of September Mr. Wilson's attention was directed 

 to the trees, several of which had the trunks and branches entirely 

 or partially covered with a very delicate web, upon which myriads 

 of a small Arachnidous insect were running to and fro, extending 

 their webs rapidly along the branches. The web was so fine as to 

 appear like a thin compact layer of varnish upon the stems of the 

 trees ; and from the vast numbers of the insects, the grey web ap- 

 peared dusted with a reddish powder, the insects being of a light 

 orange colour inclining to brown. From the web so completely en- 

 veloping the tree and obstructing the vital influence of the atmo- 

 sphere, the leaves became withered and fell. This was especially 

 the case with the plane-trees, the elms and horse-chestnuts being 

 free from them. The weather for several days previously and sub- 

 sequently was fine and sultry, but in the course of a few days a heavy 

 fall of rain, accompanied by a thunder-storm, put a stop to the injury 

 by destroying the insects. On placing a portion of the web with 

 its inhabitants in a bottle, Mr. Wilson observed that in about an 

 hour a beautiful transparent cylinder had been spun within the bottle 

 from the base of the top, impinging against the side of the bottle at 

 about half its height ; and it was remarkable that there was not a 

 single thread stretched across the inside of the cylinder, nor was a 

 single insect enclosed within it. Having completed their first cylin- 

 der, they threw a second around it more slender than the former, 

 leaving only a small interval between them. 



Mr. White considered the species to be the Trombidium tiliarium, 

 Herm., or an allied species, and distinct from the Acarus telarum, 

 Linn., and Trombidium socium, the habits of which, as described by 

 Hermann, were mentioned by Mr. White. 



Mr. Walton informed the Meeting that a specimen of the true 



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