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. 



