73 



HARDWICKE'S SCIENCE-GOSSIP. 



shells are sometimes striated like P. a/bus. Some 

 specimens collected at Minster have a reddish tinge. 

 I have taken the white variety in Thanet, and also a 

 single young specimen at Kew Gardens. The white 

 var. has also been reported as occurring in Middlesex. 



Physa hypnornm. — The mouth of this shell is some- 

 times tinged with pink. 



Physa acuta. — This is not really a British shell, 

 the only locality for it being one of the water-lily 

 tanks in Kew Gardens, where it is abundant. One 

 of my specimens has the bands 4 and 5 slightly 

 developed. 



Physa fontinalis. — This varies in size ; my largest 

 specimen I took at Ealing, with the large P. corneus, 

 it is slightly more than \ of an inch in length. I have 

 taken a single specimen of the white variety at Heme 

 Bay, living with the type. 



T. D. A. COCKERELL. 

 (To be continued.) 



AN AQUARIUM IN A BOTTLE. 



I HAVE kept small shore crabs (Carcinus mccnas) 

 in wide-mouthed glass pickle bottles for many 

 months, and also hermit crabs (Pagurus Pcrnhardi), 

 but the former do the best. Serpulae (Serpula 

 triquetral and also very small terebellae do well too, 

 but I have never been able to keep full-grown mussels 

 for more than a day or two. My plan is to fill the 

 bottle one-third full of fine sand, and place on this a 

 large stone with a piece or two of ulva growing on it. 

 This stone is tilted up in such a way, that there is 

 deep water (comparatively speaking), in the front of 

 the bottle, while behind it is only just covered. 

 "When first made a strip of paper should be pasted on 

 behind to mark the level of the water, and it should 

 always be kept up to that level with a spoonful or so 

 of fresh water, as needed, to make up for the loss by 

 evaporation. The less water there is in the bottle, the 

 better ; it will be found quite sufficient to fill it half 

 or two-thirds full (including the sand). The plan 

 suggested by Mr. Lovett (vol. xx. p. 75) will be 

 found a very good one by those who have not a cool 

 place in which to stand the bottle in hot weather. 

 If the water turns a little green, placing it in the 

 shade a day or two, I find soon remedies it. If 

 anything goes wrong, and the water turns black, I 

 pour it into a clear glass bottle, put a few pieces of 

 confervae in, and place it in the sunshine ; the oxygen 

 produced by the influence of the sunlight on the 

 seaweed soon neutralizes the offensive gases produced 

 by putrefaction, and in a short time the water is as 

 clear as ever. I do not shake the water, but let it 

 remain constantly still ; shaking it retards the 

 purifying process. Although I use bottles when I 

 have so many creatures, such as crabs, requiring 

 isolation that I scarcely know what to do with them, 

 I do not recommend the plan, except as subsidiary to 



other aquaria. A propagating glass can be bought 

 for a few pence, and this inverted and placed on a 

 suitable stand will be found by far the best. Stocked 

 with anemones, serpulae, terebellae, a young nereis, 

 periwinkles, very small mussels, and a few acorn 

 barnacles with, perhaps, one or two small prawns, it 

 will be a constant fund of amusement and instruction. 

 A few pieces of green seaweed will make it look very 

 effective, but care must be taken not to introduce too 

 much, or it will decay, and blacken the water. 

 Fish and crabs require vases to themselves, as they 

 will neither agree with the other inmates nor among 

 themselves. 



Albert Waters, B.A. 

 Cambridge. 



A NET FOR MICROSCOPISTS. 



AS the bright days increase in number, every one 

 is led involuntarily to look over his collecting 

 apparatus in anticipation of that sudden starting into 

 renewed life of all aquatic vegetation, and the 

 consequent crowds of Infusoria, Entomostraca, &c, 

 which afford all those who are keenly interested in 

 their birth and " education," such an endless amount 

 of pleasant recreation. The pleasure of such collect- 

 ing, I always think, is greatly increased by the use 

 of a convenient net, which should enable one to 

 remove any object of value, and recommence the 

 netting without unnecessary loss of time. 



The methods usually adopted for attaining this, 

 are, either to wash the muslin in a wide-mouthed 

 jar, which must therefore be carried out on all ex- 

 peditions, or to use a set of muslins, each one of which 

 when sufficiently covered with life, is removed and 

 dropped into a bottle, of necessity, large and cumber- 

 some. 



I tried the simpler of these two modes, i.e. washing, 

 for some time, but never found that the result was 

 altogether satisfactory, many specimens of worth 

 being washed out of the net, if its passage through 

 the water happened to be in the least degree hurried. 



The next that I tried was a deep conical net, 

 stretched upon a framework of cane, bent (after 

 boiling) somewhat to the shape of an iron hook, ^\— 

 Across the semicircular portion, i.e. from A to b, I 

 stretched a copper wire, not less than six inches in 

 length, which served as a finer cutwater than the 

 cane, and made a strong and effectual " scraper " for 

 such stems as those of the water lily. I had, from the 

 first, considerable difficulty in turning a net of this 

 shape inside out, and, to overcome this, at length 

 contrived one, whose construction I hope the following 

 explanations will render sufficiently clear to enable 

 those who may care to copy it to possess one similar 

 to my own. The framework is precisely the same as 

 that shown above. The muslin bag is so arranged 

 that the point of the cone comes exactly opposite to 



