254 NOTE? ox THE ECONOMY OF GYRIMS VILL05US. 



Art. XXXIII. — Xott on thi Economy of Gyrinu^ ViHosus. 

 By the Rev. A. W. Griesbach. 



Sir. — In Vol. II. pp. 530, 531, of the Emoinological Maga- 

 zine, is a communicarion by Mr. Haliday, describing a curious 

 fact in relation to the economy of Gynnus Vilk-su^. The fol- 

 lowing observation, accidentally made by myself, of the sort of 

 place in which that insect, sometimes at least, undergoes its 

 metamorphosis, may be read in connexion with it. 



On the ~ist of May last. I was by the side of the river 

 Derwent, which is distant about one mile from this village : and 

 seeing an old dead willow tree, I pulled off some of the bark, 

 and poked about among the decayed wood, to see if I could 

 find any thing. There was not much in it save " wood lice. ' 

 (oniscus?) and three small cocoons made of a whitish silk. 

 interwoven on the outer pan with minute fragments of the 

 decayed wood. These cocoons were attached to each other, 

 or were at least in contact, and contained what ^without much 

 examination) I mistook for the pupae oi Anobium tesseUatum. I 

 brought them home and put them into a pill-box, which I depo- 

 sited in a drawer, and forgot. However, by a mere chance I 

 opened this box about a month ago ; and in it were three 

 specimens of Gynnus riU.'Xsus — two quite perfect, the other 

 with crumpled elytra. They were as dark coloured as the 

 species usually is, but all of them were dead. 



The willow-tree in which I found the cocoons was a yard, 

 perhaps, from the edge of the river, and the cocoons were 

 about two feet from the ground, in the decayed wood of the 

 tree. 



On the strength of this fact, I am disposed to agree with 

 Mr. Haliday, that the specimen of Gyrinus tiUosus (which is 

 the subject of his communication) did not go through its 

 changes in the shell in which it was found. What it really 

 was doing or about to do-^whether its being there was " an 

 accidental occurrence,'' or an indication of some '' pecuharity 

 in the habits of the subgenus " to which it belongs — must, I 

 suppose, remain for the present, mere matter of conjecture. 



I am, Sir, 



Your obedient servant, 



A. W. Griesbach. 



Westote, wemr iPUfwdZ, TwHtsiire, 

 I8lk JmsvI, 1836. 



Jdl 



