Rupert Jones, on Bivalved Entomostraca. 45 



Estheria minuta long passed as a little sliell among geologists 

 nntil Prof. Quekett's microscope detected the hexagonal cell- 

 tissue of the Crustacean in fragments of the fossil : see my 

 ' Monograph of the Fossil Estherise ' (Palteontograpliical 

 Society), 1862, pages 3, 11, &c. 



Very different kinds of carapace-valves belong to the 

 Ostracoda. A synopsis of the recent British forms of this 

 great group, carefully drawn up and illustrated by Mr. G. S. 

 Brady in the ' Intellectual Observer ' for September, 186T, 

 gives us a good general view of these very interesting Bivalved 

 Entomostraca, amongst Avhich are (excepting some of the 

 Copepoda and Cladocera) the most common of the marine 

 and freshwater forms, both recent and fossil. Thus — 



Cyprid^. — Cypris ; Cypridojjsis ; Paracypris ; Notodro- 

 mas ; Candona ; Pontocypris ; Baii'dia ; Macrocypris. 



Cytherid.d. — Cy there (and Cythereis) ; Limno cy there ; 

 Cytheridea (and Cyprideis) ; Cytheropsis (to be changed to 

 " Eiccy there") ; Hy abates; Loxoconcha (= Normania) ; Xesto- 

 leberis ; Cytherura ; Cytheropteron ; Bythocythere ; Pseudo- 

 cythere ; Cytherideis ; Sclerochilus ; Paradoxostoma. 



Cypridixid^. — {Cypridina ;) Philomedes ; Cylindoleberis ; 

 Bradycinetus. 



CoxcHCECiADJE. — Coiichoecia. 

 PoLYCopiDiE. — Poly cope. 

 Cytherellid-^. — Cytherella. 



The valves of the Cypridce (Brady) are small, usually either 

 kidney-shaped, oblong, or boat-shaped, smooth or bearing 

 only faint punctation and delicate set^e, and rarely thickened 

 on the hinge-margins. The Cytherida, on the other hand, 

 though often smooth, have frequently thick and highly orna- 

 mented valves, coarsely or neatly pitted, sculptured with 

 fret-work (more or less reticulate), or bristling with spines 

 and spikes. Either ovate or oblong in many shapes, they 

 have usually thick hinge-margins, with furrows and sockets 

 for bars and teeth. The other families mentioned have 

 smooth valves ; those of Cypridina are large, thick, and 

 convex, mostly round or oval, and are marked with an 

 antero-ventral notch Conchoecia has an oblong, and Poly- 

 cope a subspherical shell ; both thin. Cytherella has oblong, 

 compressed, thick valves, usually smooth, one fitting into the 

 other somewhat like the lid of a wooden snuff-box. 



Of the Ostracoda very many are found fossil, such as 

 belonged to fresh waters, to brackish waters, and to the sea, 

 in great variety. Miinster, Roemer, Reuss, De Koninck, 

 Bosquet, Bornemann, and others have described many species 



