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sentation to one of the professors ; hut, for some reason, it was not pre- 
sented, and, returning to England, it was thrown overboard in the Straits 
of Dover. Soon afterwards a person presented himself at the British 
Museum, and offered a living specimen for sale, asking for it £5, and 
averring that it had been taken at Dover. Could it be that it was the 
same individual that was thrown overboard in the Straits 1 At all events, 
it should be borne in mind that if found in future it is a naturalized, and 
not an indigenous, animal on our coast. 
Discovery of Aquatic Hymenopterous Insects. — Mr. Lubbock, F.R.S., 
exhibited, at the Entomological Society, two species of aquatic hymenop- 
terous insects, one of which swims with its wings. They were found in a 
basin of water obtained from a pond. While examining the Entomostraca 
swimming about in it, he was struck with astonishment at observing a 
small, veritable, clear-winged insect swimming with an easy, graceful, 
jerking movement, by means of its wings. Although some of the hyme- 
noptera had been observed to descend temporarily into the water, this was 
the first which had been met with which was truly aquatic. He proposed 
to call it Polynema natans, and remarked that, in a palaeontological point 
of view, it was worthy of notice that, had it been found fossil, there 
would have been nothing to indicate that it was not a terrestrial or 
aerial animal. 
Cultivation of Oysters. — M. Coste has communicated to the Academy of 
Sciences an account of the progress of his oyster-beds on the west coast of 
France. That waves and currents carry the ova of oysters is a well- 
known fact, since the walls of newly-erected sluices are often covered with 
them ; but in the island of Re, where the inhabitants have for some 
years been engaged in cleansing the muddy sediment from their coast, the 
oysters are now permanently established. Seventy-two millions of oysters, 
from one to four years old, is the lowest average registered per annum by 
the local administration, representing a value of about two millions of 
francs (£80,000). 
Iron-banks built by Animalcules. — M. de Watteville announces, in the 
Journal de V Instruction Publique, that in the lakes of Sweden there are 
vast layers or banks of iron, exclusively built up by animalcules. This 
iron is called lake ore, and distinguished, according to its form, into gun- 
powder, pearl, money, or cake ore. In winter, the Swedish peasant, who 
has but little to do at that season, makes holes in the ice of a lake, and 
probes for an iron-bank ; then, letting down a sieve, the loose ore is 
shovelled into it with a ladle, mixed, of course, with sand, which is got rid 
of by washing it in a cradle. One man may obtain a ton of iron ore per 
diem by this process. 
Fleet of Portuguese Men-of- War ( Physalia pelagica ) off the Isle of 
Wight. — This beautiful Medusa, which, as its name indicates, is oceanic, 
has lately made its appearance in great numbers off the Isle of Wight 
after a storm. Many of them were alive, and lived two days in a basin of 
salt-water. They are very rarely taken on British shores. 
The Royal College of Surgeons of England has recently purchased for 
its museum a collection of specimens of animals from Professor Hyrtl of 
Vienna. The chief object of interest was the skeleton and stuffed skin of 
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