308 THE ESSEX NATURALIST These descriptions of the habitat refer only to the area studied, i.e. Benfleet Creek. If these observations and deductions are to be confirmed and checked a great deal more work on similar lines in other suitable localities is needed. References Allen, E. J. & Todd, R. A. (1900). The fauna of the Salcombe Estuary. J. mar. biol. Ass. U.K., 6: 151-217. Bassindale, R. (1938). The Intertidal Fauna of the Mersey Estuary. J. mar. biol. Ass. U.K., 23: 83-98. Bassindale, R. (1943). Studies in the Biology of the Bristol Channel, XL J. Ecol, 31, 1. Beanland, F. L. (1939). Sand and Mud Communities in the Dovey Estuary. J. mar. biol. Ass. U.K., 22. Crawford, G. I. (1937). A review of the Amphipod Genus Corophium, with notes on the British species. J. mar. biol. Ass. U.K., 21 : 589-630. Dales, R. P. (1950). The reproduction and larval development of Nereis diversicolor. J. mar. biol. Ass. U.K., 29: 321-360. Ellis, W. G. (1933). Calcium and the resistance of Nereis to brackish water. Nature, London, 132: 748. Elmhirst, R. (1931). Studies in the Scottish Marine Fauna—The Crustacea of the sandy and muddy areas of the tidal zone. Proc. roy. Soc. Edinb., 51. Fraser, T. J. (1932). Observations on the fauna and the constituents of an estuarine mud in a polluted area. J. mar. biol. Ass. U.K., 18: 69-86. Hart, T. J. (1930). Preliminary notes on the Bionomics of the Amphi- pod Corophium volutator, Pallas. J. mar. biol. Ass. U.K., 16: 761-789. Holme, N. A. (1949). The fauna of the sand and mud banks near the mouth of the Exe Estuary. J. mar. biol. Ass. U.K., 28: 189-237. Howes, N. H. (1939). The ecology of a saline lagoon in South East Essex. J. Linn. Soc. (Zool.), 40. Knudsen, M. (1901). Hydrographical Tables. Reprinted, Copenhagen, 1953. Nicol, E. A. T. (1953). The ecology of a Salt Marsh. J. mar. biol. Ass. U.K., 20: 203. Moore, H. B. & Spooner, G. M. (1940). The ecology of the Tamar Estuary, VI. An account of the macrofauna of the intertidal muds. J. mar. biol. Ass. U.K., 24: 283-330. Pearse, A. S. (1928). On the ability of certain marine invertebrates to live in dilute sea-water. Biol. Bull., 54: 5. Percival, E. (1929). Reports on the fauna of the estuaries of the Tamar and River Lyn. J. mar. biol. Ass. U.K., 16: 81-108. Rees, C. B. (1940). A preliminary study of the ecology of a mud flat. J. mar. biol. Ass. U.K., 24: 185-199. Reid, D. M. (1929). On some factors limiting the habitat of Arenicola marina. J. mar. biol. Ass. U.K., 16: 109-116.