22 THE ENTOMOSTRACA OF 



near the Reculvers, 1 Kent, by Mr. Prestwich, and at Chislet, between Wear Farm and 

 the Grove Ferry Station, by Mr. J. Brown, of Stan way ; to both of whom I am 

 indebted for a liberal supply of specimens. At the two last-mentioned localities the 

 carapaces are not so strongly tubercled as they are at Grays. 



Cyprideis torosa is also a recent species, living in the Gravesend ditches, where 

 Mr. Pickering (who kindly favoured me w T ith my recent specimens of this species) 

 found it in great numbers, attached to the cases of Caddis- worms, " in a ditch which 

 runs on the land-side of the Thames Bank, between Gravesend Town and Coal House 

 Point, near an old mill : the water flowing into and not from the Thames, except at 

 high tides." 



Sub-family — Cytherin^e, Dana. {Cylherida, Baird.) 



In this second sub-family of the Cyprida (Dana) we meet with similar difficulties in 

 the allocation of the fossil carapaces to generic forms as among the Cyprince ; for, 

 although the carapaces are readily arranged into natural groups according to their 

 peculiarities of structure, yet these peculiarities do not necessarily indicate generic 

 differences among the animals to which they belonged ; and, in fact, in this branch of 

 palaeontology, as in others, we have still to wait for an intimate knowledge of living 

 animals before we can confidently speak of the exact relations of the fossil remains of 

 earlier creatures, which they more or less closely represent. Cytheretta, Bairdia, 

 Cytherideis, Cytheridea, and Cythereis exist in the present seas, as well as Cythere proper; 

 and favorable opportunities will, it is hoped, occur for their minute examination in a 

 fresh state. 



The Cytheres of the Baltic have been carefully examined by Liljeborg and Zenker^ 

 but the result of their examinations does not much assist the palaeontologist in the 

 comparison of the recent and fossil forms. The views of these two authors on the 

 synonymy of some of the best known of the recent species are at variance ; 2 nor do 



1 Where it seems to have inhabited brackish water ; ' Quart. Journ. Geol. Soc' xi, p. 1 12. 



2 According to Liljeborg, the Swedish species which he examined are three, viz. : 



Cythere gibbera, Miiller. 



— viiunis, lb. Syn. C. lutea, Midler ; C. albomaculuta, Baird ; and 



C. alba, Baird (young). 



— nitida, Liljeborg. 



Zenker arranges his species from the Cattegat and the Baltic thus — 



Cythere lutea, Miiller. Syn. C. reniformis, Baird. 



— gibba, lb. Syn. C. ffibbera, Miiller. (Male and Female.) 



FLAVIDA, lb. 



— viridis, lb. Syn. C. variabilis, Baird. 



