RECENT BRITISH OSTRACODA. 



367 



Anterior margin broad, well rounded, and encircled by a narrow flattened lamina. Pos- 

 terior extremity narrow, ronnded. Ventral margin slightly sinuated in the middle. 

 The dorsal margin has a gibbous elevation a little in front of the middle, from which it 

 slopes steeply backwards and more gradually towards the front. Dorsal aspect oval, 

 tumid, widest in the middle, and tapering equally towards the somewhat sharply painted 

 extremities. Anterior view nearly circular, the height being very slightly greater than 

 the width. The surface of the shell is slightly roughened, presenting a scaly appearance 

 the result of a peculiar reticulated sculpturing. Colour olivaceous or brown. Postab- 

 dominal rami rather stout; the two terminal claws about equal in length ; lateral setae 

 short. 

 Length -jj in., height ^j in. 



I have found this species near Belsay, and in pools on the bents north of Seaton Sluice, 

 Northumberland; at Penham, near Newcastle, at Whitburn and Boldon Plats, near 

 Sunderland, and near Cotherston, Yorkshire. It has been taken also by the Rev. 

 A. M. Norman at Sedgefield and at Osterley Park, near Brentford. 



C. tessellata is, in many cases, easily distinguished by the peculiar sculpturing of the 

 valves, which, in fine specimens, and with good illumination under the microscope, 

 resembles an exquisitely wrought pattern of filigree-work. The reticulations of which 

 the ornament is composed are largest towards the extremities of the valves ; across the 

 middle of the carapace they are not very conspicuous, the shell-structure being there 

 much more condensed. The junction of the reticulation of the extremities with that of 

 the closer central band is shown in PI. XXIII. fig. 43. It will be seen that the tendency 

 to a radiate arrangement is continuous throughout. Occasionally the surface-marking is 

 almost entirely absent, the shell being nearly as smooth as that of Cyprisfusca ; some 

 trace, however, of the peculiar ornament is always visible. 



Oypris tessellata appears to haunt only small grassy pools, where the water is con- 

 siderably impregnated with organic matter. At least I know of no instance of its capture 



in lakes or large sheets of water. 



My original reference of this species to C. affinis, Pischer, seems to have been an error. 

 I had not at that time seen Pischer's monograph, and judged of the species from the 

 figures given by Lilljeborg, which doubtless refer to the present species, but agree much 

 more closely with Pischer's figures of C. tessellata than of C. affims. 



10. Cypuis clayata. Baird 



Mag. ZooL & Bot. i. p. 137, t. v. fig. 16, 1837 , Brit. Entom. p. 157, t. ™ 



Crust 



- Shell oblong, narrower at posterior extremity than anterior, which is rather flattened 



3 ' r e , • n \„u chanpd The valves have the upper 



givmg the shell the appearance o being f^^ > ^ Mn ^ but £* 

 margin elevated, and the lower nearly .taught. They a c s *o* m 



round the margin with short hairs ; their colour is of a light grej , w 



coloured ray running from the centre towards the posterior extremity ri^J»< - 



distinctly marked with an orange-coloured spot. The ant enns and J^jJ"*^ 



Pared with the size of the shell. The filaments of both pan-s of antenme ai e plumose. 



