HARD WICKE ' S S CIENCE- G O SSI P. 



163 



ZOOLOGY. 



Free Swimming Rotifers— A Suggestion for 

 A Rotifer Society. — The rotifer which Mr. Lord 

 has figured and described in the last number of 

 Science-Gossip is very common, and if Mr. Lord 

 will consult Pritchard again, he will find his Colurus 

 described under the head of Lepadella, If water 

 known to contain rotifers be left for some time, the 

 species in question will be found to be one of the 

 last survivors ; it may be taken during the winter, 

 under ice, and seems to act as a sort of scavenger, 

 thriving on food which all other species disdain. 

 Lepadella is one of the euchlainida, and bears a very 

 close resemblance to salpina in its structure, and in 

 the arrangement of its carapace. As a constant 

 student of the rotifers, I have often felt the want of a 

 satisfactory text-book, to do for them what Saville 

 Kent has done for the Infusoria, and I am glad to be 

 able to inform Mr. Lord that the rumour he has 

 heard is well founded. Dr. Hudson favoured the 

 Bristol Microscopical Society, at one of its meetings 

 last year, with a sight of the drawings for his new 

 Monograph on the Rotifers, and it is impossible to 

 speak too highly of their beauty, and, which is 

 still more important, of their accuracy. As to the 

 probable date of publication, I am sorry to say that 

 I can give Mr. Lord no idea. Those who have only 

 studied the rotifers as a means of amusement can 

 hardly be aware of the wide field for real scientific 

 work offered by our British species alone. New ones 

 are constantly being found, and even of the best 

 known of all species, the Rotifer vulgaris, the male 

 has yet .to be discovered. I think I am well within 

 the mark in saying that of all known species number- 

 ing about two hundred, at least seventy per cent, of 

 the male has yet to be discovered. If a society could 

 be formed of workers in this branch of science, the 

 very fairy-land of microscopy, the members of which 

 would exchange drawings and descriptions of any 

 unfamiliar forms they might meet with, and perhaps 

 even samples of water containing the rotifer alive, 

 which can easily be done through the parcels post, 

 the result would probably be a very great stride in 

 our knowledge of the subject. Should any of your 

 readers feel inclined to join a rotifer society, I shall 

 be very glad to receive communications and sugges- 

 tions from them, and to do anything I can to promote 

 the formation of such a society. — EdzvardC. Boiisfield, 

 L.R.C.P. Loud. 



Fish and Air. — The reason Mr. Finch's gold 

 fish gulps air above the surface of the water is that 

 it finds insufficient oxygen in the water to support 

 life. Not being provided with lungs, of course it can't 

 do this with impunity. The poor animal makes the 

 best of a bad job by carrying this air to the bottom 

 of the tank ; so as to get it mixed with water and duly 

 passed over its gills. In doing so, much of the air 



escapes from its mouth " in a succession of bubbles." 

 It cannot be too often reiterated that the changing 

 of water is fatal to aquarium keeping. You can't 

 get your water pure enough unless you keep it 

 exposed to sunlight and air. Water introduced into 

 an aquarium to make up for loss by evaporation 

 should always be kept a month or two. I have seen 

 a small quantity of apparently pure water set up 

 decomposition in a few days and poison a whole 

 tank. Again, never keep the more complex or 

 highly organised water plants for the evolution of 

 oxygen— they are far too liable to damage and decay. 

 The minute green confervse, which come, as it were, 

 spontaneously, are the only plants for your purpose. 

 As far as I can see they elaborate infinitely more 

 oxygen in proportion to the space they occupy and 

 they grow on every solid object in the tank. They 

 are welcome and longed-for guests in a newly set-up 

 aquarium which is never ready for animals till they 

 appear. Always look on fresh unkept water from the 

 tap, river, or sea, and the higher order of water 

 plants, as so much poison introduced into your tanks, 

 and your animals will not adopt any extraordinary 

 or fatal habits, but will confine themselves to the 

 ordinary routine of life, — Jo/m y. Stevens. 



Gloucestershire Slugs. — Since the publication 

 in the April number of Science-Gossip of a note by 

 Mr. Dennison Roebuck, of Leeds, upon the Glou- 

 cestershire slugs, I have met with some at Brins- 

 combe, near Stroud, which he has pronounced to be 

 the var. bicolor of Arioi ater. He also tells me that 

 the specimens I sent him were the first he had seen 

 from any English locality, though he had received it 

 last year from co. Waterford, Ireland. — E. J. Elliott. 



The House-Fly. — Can any of your readers tell 

 me where to find the eggs of the common house-fly, 

 Ilomalomyia ca?ticularis (Linn.), or whether it is 

 possible to breed them in captivity ? — E. W. E. 



British Shells. — Can any reader inform me 

 whether any marine shells have been discovered 

 since the pubHcation of "British Conchology"? 

 Also whether any of the numerous species said to 

 have been found in Britain, but considered by Dr. 

 Jeffreys as doubtfully British, have been since found 

 on any of the British coasts? — T. D. A. Cockcrcll. 



Wild Cat in Kent. — About a month ago a 

 friend of mine saw a wild cat in a wood near 

 Maidstone. He was sitting on a stile, and happen- 

 ing to look round, saw it sitting on the path glaring 

 at him. Directly it saw it was observed, it made a 

 spring through the hedge and disappeared. But 

 what my friend saw of it was enough to prove to him 

 that it was a true wild cat. It had a very short and 

 thick tail, and altogether answered to the description 

 of a true Felis cat us, — dl. C. Brooke. 



