CRUSTACEANS proper, which are limited to the last kind of habitat. A diligent and prolonged inquiry after these curiosities for a great while led to nothing but vague information and unfulfilled promises, until, at length, a lecture delivered to a working class audience produced the desired result. Of Niphargus aquilex, Schiodte, Mr. Spalding has since then from time to time very obligingly supplied me with living specimens from his well at Rusthall, Tunbridge Wells. Some of them have lived very inex- pensively for months in a small glass jar supplied with nothing but clear water. Out of respect to their former domicile their new home was kept in the shade. Niphargus fotjtanus, Spence Bate, has been taken by Mr. Lubbock (now Lord Avebury) ' in a well at High Elms in Kent.' ' Between these two species there is a considerable difference in the second pair of limbs, which have the hands elongate pear-shaped in N.fontams, but subtriangular, short and broad in N. aquilex. Their colourless transparency at once distinguishes these well-shrimps from the greenish or brownish Gammarus, but there are several other points of difference. If attention be turned to the terminal appendages, known as the third uropods, those in G. pulex will be found to have the two branches not very unequal, but in Niphargus the inner branch is rudi- mentary, while the outer is very elongate and distinctly two-jointed. Of marine species Melita palmata (Montagu) has been sent me from Whitstable by Mr. G. S. Saunders, F.L.S., together with Jassa pul- chella. Leach, which till recently has been by a misconception trans- ferred to the genus Podocerus. The singular mud-burrowing Corophium volutator (Pallas) under the untenable name C. longiconie, Latreille, is recorded by Leach who says that it ' Inhabits the coast of the European Ocean. At low tide it may be observed crawling amongst the mud. It is very common at the mouth of the river Medway, from whence we have received a vast number of specimens.' ' For Capreila linearis (Linn.) from Whitstable I am indebted to Mr. G. S. Saunders. While all the other amphipods here named belong to the tribe Gammaridea in which the pleon is highly developed, this last species belongs to the Caprellidea in which the pleon is almost evanescent. In this tribe the species of the family Caprellidae from their extreme tenuity have been called spectre-shrimps, and from their habit of bowing with the front part of their bodies while with their hind feet they cling to seaweeds they have also been called praying shrimps. Adam White, however, gives to C. linearis the elegant name of ' Pennant's Skeleton Screw.' ' In the Entomostraca we no longer find that steadfastness of pattern which can be traced throughout the Malacostraca, allowing us to believe, in spite of all existing exceptions, that between the eyes at one end of the animal and the telson at the other there are or have been nineteen body- segments each with its pair of appendages. In the Entomostraca the body-segments may be more in number, or as is generally the case they 1 British sessik-eyed Crustacea, i. 321. 2 Encyclopaedia Britannica (5th Ed.), Art. Annulosa, p. 426 (1S16). 3 Popular History of British Crustacea, p. 214.
