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 A HISTORY OF BERKSHIRE county. To credit the earlier of these to carcinology might not be quite so fair. It sprang rather from an unnatural union in the circle of the sciences, being got as a breeder might say by ichthyology out of etymology. The story works out in this way. In the first place we find the Messrs. Lysons stating in their well known work upon Great Britain that ' the principal rivers of Berkshire are the Thames, the Kennet, the Loddon, the Ock, the Lambourn, and the Auborn.' 1 Secondly, they declare that ' the fish of the Ock are pike, perch, gudgeon, roach, dace, and crayfish.' 2 Thirdly, through other sources we know that from the old German krebiz, which answers to the new German krebs, came either independently or through the French ecrevisse our old English crevisse. All in good time with our well known linguistic skill we modified this into crayfish, and finally by this trick of language writers, more bent on the pleasures of angling than on the technicalities of systematic zoology, have been led to include a long- tailed decapodous arthropod among vertebrate fishes. A more recent authority, better acquainted with the proper classification of the cray- fish, also guarantees its presence within these borders. But his warrant too may be regarded as to some extent accidental, since it depends on his mentioning the Kennet as one out of the many rivers of England in which this species is found. Speaking of the sides of rivers in general, Dr. Hamilton says : Of the Crustacea two will occasionally come under notice : 1. The crayfish (Astacus fluviatilis) or the river lobster (Aitakos being the name by which the Greeks called the lobster) is found in many of our rivers. Then after noticing its colour and the miscellaneous character of its food he continues : Owing to some unknown cause, the crayfish has entirely died out from the upper part of the river Kennet, and consequently the trout have lost a most important food-supply ; and it is possible that the redness of the flesh for which the trout in this river were noted, and which is not now so universal, was due in a great measure to this crustacean, to the young of which trout are extremely partial. May not the cause arise from the absence in the water of ingredients which were necessary for the formation of the shell ? 2. The freshwater shrimp (Gammarus pulex) is extremely common in all springs and rivers, particularly where decaying vegetable matter has accumulated. It generally keeps near the bottom and swims on its side with a kind of jerking motion, and feeds on dead fishes or any other decaying matter. In some parts of the Kennet this crustacean is to be found in great numbers. 8 The second species of this reference will be discussed hereafter. The first is more properly called Potamobius pallipes (Lereboullet). Not every reader can be expected to care about the technical names of all the animals which perhaps he captures with zeal, eats with satisfaction, 1 Magna Britannia : being a precise Topographical Account of the several Counties of Great Britain, by the Rev. Daniel Lysons, A.M., F.R.S., F.A. and L.S., and Samuel Lysons, Esq., F.R.S. and F.A.S. Volume the First, containing Bedfordshire, Berkshire and Buckinghamshire (1805), p. 193. Auborn is elsewhere spelt Aubourn. * Loc. cit. p. 196. 3 The River-side Naturalist: Notes on the various forms of Life met with either in, on, or by the Water, ot in its immediate vicinity, by Edward Hamilton, M.D., F.L.S., F.Z.S. (1890), pp. 296, 297. I2 4