^58 



Retfvspective Criticism, 



" Three aeronautic spiders ascended from the same spoty when each moved 

 in a different direction," &c. (p. 81.) Now, that no collusion maybe sus- 

 pected in the case, it may suffice to mention, I have not the honour to 

 know Mr. Thompson personally, and have had no communication whatever 

 with him ; nor is it likely he had seen my work on aerial electricity. This 

 was published in December last, and Mr. Thompson's communication ha^, 

 for the first time, appeared in the present Number (Jan.). How long it has 

 been in your possession I know not, but of its existence I at any rate was 

 ignorant. It is palpably evident that in the one case the projectile thread 

 was independent of a current of air. The naturalist of Selboume declares 

 the same thing, and he was a keen and cautious observer ; and it seems 

 also clear that in both the floatage owned another cause than the ascent of 

 calorific emanations. I have, however, other facts, which I shall elsewhere 

 adduce, and that I believe will set the matter to rest, — J. Murray. Car- 

 mariheUy April 2, 1830. 



Nidm on a Rush. — Sir, The nidus figured in VoL II. p. 104. is not, I 

 believe, the work of an aquatic spider, as supposed by your correspond- 

 ent, and also by our celebrated entomologist, the Rev. W. Kirby (Vol. IL 

 p 405.), nor is it so uncommon as it is considered by that indefatigable 

 and successful collector. Captain Blomer. (Vol. II. p. 303.) I have found 

 it on high stalks of grass in shallow road-side drains, which are dry in 

 summer and at other times when water does not abound : this shows that 

 it is not the nest of an aquatic spider. I have to mention another circum- 

 stance respecting it, which seems to have escaped the notice of others, and 

 which will account for its supposed rarity. This snow-white silken fabric 

 is concealed by a covering of mud soon after it is spun. Several years ago, 

 when I was on an entomological ramble in the neighbourhood of Stowey, 

 in Somersetshire, I found a few of the nestSy just like those figured. On 

 searching further, I met with one partly covered with mud, which led me ta 

 the discovery of others thoroughly plastered over. In this state they resem- 

 bled bits of dirt splashed from the road on the stalks of grass. The plaster 

 was evidently collected by the parent spider • from the moist bed of the 



drain from which the grass 

 grew. I could have collected 

 dozens of the nests in the dif- 

 ferent states : the plastered 

 ones were the most numerous. 

 I brought home a few, but the 

 young spiders never came out, 

 and I regret that I cannot in- 

 form you what species perform 

 this ingenious work, for 1 con- 

 sider it as beautiful and in- 

 teresting as any thing recorded 

 in the history of insect architecture. I have reared young spiders from 

 analogous nests, a sketch of which I send herewith, together with figures 

 of our beautiful nidus in its unplastered and plastered state, {fig. 1 13.) — 

 — W. B. B. W. February 20. 1830. 



The Hessian F/j/. — The insect figured by Mr. Kirby (Vol. I. p. 227.) is 

 evidently one of the Ciilices; but he refers it to the Tipula genus. 

 The Tipulae, I believe, are destitute of a trunk, with which the Culices are 

 furnished. The resemblance of some of the smaller species of these two 

 genera is so close, that they have been confounded by both Goedart and 

 Swammerdam. — A. L. A. Alnwicky April 7. 1830. 



Fly^s Eye under the Microscope. — By far the most beautiful phenomenon 

 of this kind is exhibited in the picture of the window reflected from the 

 numerous facets of the compound eye of the Libellula or dragon fly, and 

 this multiplied image becomes extremely curious, being in motion, when an 



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