4 A REYISIOX OF THE BRITISH SPECIES OF 



amongst the numerous collections -which I have had to examine. 

 There will certainly, for many a year, be plenty of scope for the 

 energy of collectors even if they limit their researches only to the 

 discovery of new species. The two counties of Northumberland 

 and Durham present probably as good an area as can anywhere 

 be found for the prosecution of this kind of work, their numer- 

 ous salt-marshes, moorland tarns and pools offering a fine field 

 for research. Several of the most interesting species noticed in 

 the following pages have been found within the confines of the 

 two counties which we have been used to consider as the proper 

 hunting ground of the Tyneside Field Club ; but in these days 

 of rapid and easy railway communication there seems no reason 

 to restrict the survey of the Club within what are frequently 

 mere arbitrary boundaries resting upon no important physical 

 characters. 



In the preparation of this paper I have had the very valuable 

 help of many friends, to whom my best thanks are due : — to the 

 Rev. Canon Norman, D.C.L., F.R.S., for a fine collection of 

 tow-net and hand-net captures from almost all parts of England 

 and Scotland, and from Lough Neagh and other localities in 

 Ireland; to Mr. Thomas Scott, F.L.S., of the Scottish Fishery 

 Board, for many very interesting species from various districts 

 of Scotland ; to Mr. D. J. Scourfield, for numerous gatherings 

 from the neighbourhood of London. To Professors Gr. 0. Sars 

 of Christiania, B. W. Thomas of Chicago, M. Richard of Paris, 

 and Herr S. A. Poppe of Vegesack, Hanover, I am also much 

 indebted for the communication of specimens and other valuable 

 information. 



As regards the illustrative drawings now given, it may be 

 explained that I have not thought it necessary to figure over 

 again such species as were fairly well done in my Ray Society 

 Monograph, except that in the genus Cyclops I have given in 

 each case a single new figure of the entire animal. These, I 

 think, will be useful as affording a ready means of comparison 

 as to the external characters of the species. I regret that 

 Cyclops Ewarti forms an unavoidable exception to this state- 

 ment, no specimens of that species being attainable, 



69 



