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 CRUSTACEANS observers. Dr. G. S. Brady, Dr. David Robertson, and the Rev. Dr. Norman. In a joint paper the first two say : ' The Entomostraca of the tidal waters of Norfolk, Suffolk, and the Cambridge fen district constitute so remarkable a group that it seems best to speak ot them separately ; and in so doing we shall call the area to which we refer the East-Anglian district, understanding by that term the whole tract drained by the rivers Nene, Cam, Bure, Yare, and Waveney." They think it possible that the fen district of Lincolnshire may also have been continuous with the other tract in former times. They discuss the changes which the physical features of East Norfolk have undergone, making a sea-covered bank the site of a large town, and leaving lakes and tortuous streams where was once a marine expanse. They give evi- dence that the process of silting up is still at work. Finally, they draw the following conclusions : ' There can be no difficulty, then, in under- standing how a fauna, introduced when the whole East-Anglian district was overspread by the sea, should hold its ground for a lengthened period, while its habitat was year by year becoming less subject to marine influences, and that the more hardy or more plastic species should remain even after fresh water entirely usurped the place of salt, while at the same time a new fauna derived from the landward side was also gradually establishing itself, as the conditions of existence became more favourable.'^ From numerous surface gatherings the two authors obtained a considerable collection of Entomostraca belonging to various groups, but these were swimming species of purely freshwater character, such as might have been found, they explain, in any British waters of like extent. In their dredged material, on the other hand, they found several new and peculiar Ostracoda. As these little bivalved crustaceans in outward appearance are just like bivalved molluscs, when only empty valves are found, confusion easily arises. Accordingly, what was de- scribed by Brady and Robertson in 1870 among the Ostracoda of the Norfolk Ouse as Goniocypris mitra nov. gen. et sp., is explained by Brady and Norman in 1889 to be the fry of the mollusc Anodonta cygncea? Another form, Polycheles stevensoni, which they found in the Ouse and many other localities, was a genuinely new discovery, both as to genus and species ; but the generic name was twice changed, first into Dar- winella and then into Darwinula, both Polycheles and Darwinella being pre-occupied. The species now stands by itself in the Darwinulida?, third family of the section Podocopa. Argillcecia aurea, Brady and Robertson, is made a synonym of it by Brady and Norman in 1889.* In the Cytheridse, the fourth family of the same section, stands Meta- cypris cordata, another new genus and species, discovered by Brady and Robertson in Wroxham and Barton broads, and at other East-Anglian ^ Monograph of the Marine and Freshwater Ostracoda of the North Atlantic and of North- Western Europe, section I., ' Podocopa,' by George Stewardson Brady, M.D., F.R.S., F.L.S., and the Rev. Alfred M. Norman, M.A., D.C.L., F.L.S. ; Trans. Royal Dublin Soc, ser. 2, vol. iv. p. 120. I 193 O
 * Annals and Magazine of Natural History, ser. 4, vol. vi. p. 3, 1870. * Ibid. p. 4.
 * Ibid. p. 122.