CYTHEREIS. 175 



1. Cythereis Whiteii. Tab. XX, figs. 3, 3 a* 



Shell oblong, flat, thin, somewhat narrower at one end 

 than at the other. Larger extremity rounded ; the nar- 

 rower extremity somewhat truncated and strongly toothed. 

 The anterior margin and rounded extremity are crenulated 

 throughout the whole of their length, and have placed 

 above them a sort of shelf or pinched-up fold, which runs 

 parallel with the margm, and which is strongly serrated. A 

 sharp crest, which is crenulated, runs along the centre of the 

 valve. The posterior margin is nearly straight and smooth. 



This species is remarkably handsome, and approaches 

 near the Ci/pridina serndata of Bosquet (Entomost. de 

 la Craie de Maestricht, t. iv, f. 2, a, h), but is distin- 

 guished from it by being shorter and broader, and by the 

 margin being continued straight to the end, and not in- 

 terrupted and toothed, as in that species. 



Hab. — Torquay, in sand ; W. C. Williamson, Esq. 

 Tenby, in sand ; T. Rupert Jones, Esq. 



2. Cythereis Jonesii. Tab. XX, fig. l.f 



Shell thick, oblong oval, rather broader at one extre- 

 mity ; the narrower end flattened, with seven strong teeth 

 projecting from the edge, the outer teeth on each side 

 being the strongest ; the broader extremity rounded and 

 convex. The centre of the shell is plane and smooth, and 

 round the whole circumference there is a raised border or 

 narrow plate, which is perforated at frequent intervals by 

 open loop-holes. 



This species approaches the Cytherhia coronata of 

 Roemer (vide Jahrbuch, 1833, t. vi, f. 30) in structure, 

 but differs totally in form, and in having the strong teeth 

 at narrow^ extremity. 



Hah. — Isle of Skye, in sand ; W. C. Williamson, Esq. 



* Named after Adam White, Esq., of the British Museum, well known 

 as the able describer of many new species of Crustacea. 



f Named after T. Rupert Jones, Esq., author of the ' Entomostraca of 

 the Cretaceous Eormatiou,' whose attention in forwarding me specimens of 

 Ostracoda for examination I thus gladly acknowledge. 



