SCIEXCE-GOSSIP. 



Collecting Diptera. — I am thinking of taking 

 up the study of the Diptera, and should be glad if 

 you would be so kind as to give me a few hints as 

 to the best way to set about it. I know only a very 

 littls about entomology, having hitherto taken no 

 interest in insects other than moths and butterflies. 

 Is there any book on the dipterous insects to be 

 had ? Perhaps some of the entomological readers 

 of " Science-Gossip" would help me to a wrinkle 

 or two. — E. P. Oates, Moat Bank, Alrewas, Burton- 

 on-Trent; April 16/A, 1895. 



Preservation of Colours of Shells. — I find 

 that the colours seem to sink when certain 

 species cf shells become dry. Could any 

 of your readers, through the pages of Science- 

 Gossip, tell me the best means of fixing the colours 

 without having to use anything in the nature of a 

 varnish. From some specimens I have purchased 

 from dealers, I conclude there is something that is 

 used which will stand washing, and at the same time 

 does not give the shell an appearance of having 

 been artificially treated. —A. K. Lane, 11, Geneva 

 Road, Fairfield, Liverpool. 



Valvata fiscinalis as a Spinner. — I do not 

 know whether Valvata piscinalis is well-known as a 

 thread-spinner ? It is not included in the lists 

 which I have seen. A few days ago I noticed some 

 immature specimens from this neighbourhood, 

 while in captivity, actively engaged in thread- 

 spinning. Their usual mode of procedure was to 

 crawl up the side of a glass vessel nearly to the sur- 

 face of the water: they then gave one or two 

 twisting motions, and crawled out on the under 

 surface of the water, leaving a thread joining them 

 to their point of departure. They then either sank 

 slowly, remained floating, or sank about half way, 

 where they stopped. In either case the thread 

 could easily be demonstrated with a pin, and though 

 in most cases sufficiently strong to raise them to 

 the surface, I have not been able to withdraw them 

 entirely from the water by its means. — Arthur E. 

 Boycott, The Grange, Hereford; April 8th, 1895. 



Luminous Centipede. — As I was coming up our 

 garden last night I saw what appeared to be an 

 unusually bright glow-worm. It was raining fast and 

 so cold that this sight surprised me. On picking it 

 up it turned out to be a slender pinkish-coloured 

 centipede about one and a half inches long. I 

 carried it indoors and placed it under a glass, but 

 did not notice any further luminosity. I am 

 curious to know if this is a special species of 

 centipede gifted with the glow-worm's power of 

 showing a tiny lamp, or whether it was accidental. 

 The creature is quite lively this morning, so the 

 light could not have been due to decomposition, 

 such as I have seen on dead fish or fungi. Perhaps 

 one of your readers could enlighten me on this 

 subject. I will endeavour to keep the centipede in 

 case anyone cares to identify the speues. — Annie M. 

 Mann, Grange House, Chigu-ell, Essex; M.irch 21st, 1895. 



The late Frost. — I have read with great 

 attention the paper on " The Frosts of the Century " 

 (ante page 3). As I live on a hill, in a house facing 

 east, with windows and doors none too close-fitting, 

 my experience of the frost was severe. I have 

 many reminiscences also of the frost of 1881 and 

 1891, such as the lid freezing to the teapot, water 

 freezing in bedroom over a fire-heated room, etc. 

 This year an unprecedented thing happened. The 

 ink, corked down, five feet from the fire-place 

 (there was a fire all day), was frozen, so also 

 was ink corked and shut in a desk. Everything 

 liquid in the house, excepting turpentine and cil 

 (olive oil did freeze) was frozen. A hot-water 

 bottle in a bedroom — a fire was in the room 

 every night — although within a yard of the fire, 

 split all down. The water for breakfast was 

 placed in the fender, and was frozen in the morn- 

 ing. I have never known the ink to freeze before this 

 year. — S.A. Ladkin, Sioue, Wecdon; March 8th, 1895. 



Pigmy Flints. — I have read with interest the 

 Rev. Mr. Gatty's paper in Science-Gossip (ante 

 page 36), on the subject of " Pigmy Flints." He 

 there ascribes the chipping on the edges of these 

 flints to human workmanship put on the flint. I 

 have been long acquainted with pigmy flints, and 

 have come to regard the flaking or chipping on 

 their edges not as the result of workmanship be- 

 stowed on the flint before being used, but as having 

 resulted from usage of the flint. By way of illus- 

 tration I have just taken a small crescent flint, 

 which happens to be an ancient flake, about the size 

 of the crescent figured on page 36. I examined it 

 with my lens, and found that there is no chipping 

 on any of the edges. I then used it, as one w-ould 

 do a bit of glass, in throwing off a few shavings 

 from my hammer shaft, and again examined it 

 with my lens. I found that the edge I had worked 

 with was chipped along its entire length. I have 

 also long since come to the conclusion that what is 

 known in archaeological language as "secondary 

 chipping " is not the result of workmanship be- 

 stowed on the flint, but as that of work done by it 

 after the flake had been trimmed. — /. Smith, Monk- 

 redding, Kilwinning; April, 1895. 



Curious Behaviour of Caddis- Worm. — Mr. H. 

 B. Guppy's note on " Caddis- Worms and Duck- 

 weed" (ante page 11) reminds me of a curious and 

 amusing incident which took place in my aquarium 

 last summer. I had three specimens of these 

 larvae, and found great interest in watching their 

 movements and habits. Two of them had cases 

 composed entirely of sand grains and very small 

 fragments of other material, whilst the third was 

 distinguished by the addition of a small twig and a 

 piece of straw, both of which overlapped the ex- 

 tremity of his case by about a quarter of an inch. 

 I noticed that it was continually followed about by 

 one of the other caddis larvae, which was often to 

 be found hanging on to the end of the twig. In 

 about three days it had succeeded in detaching the 

 portion of the twig that projected from its neigh- 

 bour's habitation, and was wearing it about upon 

 its own back. Not even then satisfied, it shortl}' 

 afterwards commenced a similar attack upon the 

 piece of straw, and on securing possession of a 

 fragment, perched it sideways just over its head. 

 I ought to mention that there was plenty of sand 

 and pieces of water-plants eaten off by snails in 

 the aquarium, so that lack of building material 

 cannot be urged as the reason for this caddis- 

 worm's behaviour. — F. G. Bing, 16, Loner Coombe 

 Street, Croydon ; April 6th, 1895. 



