KNOWN SPECIES OF MARINE OSTRACODA. 381 



23. Cythere areolata, n. sp. (PI. LXII. fig. 2, a-d.) 



Triangular, oblong, cuneiform. Ventral margin convex ; dorsal margin elevated and 

 angular at the anterior hinge, forming two or three rounded protuberances behind. 

 The posterior border is very narrow and rounded off; the anterior broad, arched, and 

 angular at its extremities. Dorsal aspect ovate, angular, keeled. End view triangular, 

 its angles well marked, base convex. Surface of shell finely punctate, and marked out 

 into small areolae by a delicate reticulated ribbing. Near the middle of the valve is a 

 strong longitudinal rib, and one or two smaller ones between it and the ventral margin. 

 On the dorsal side of the median rib the valve is covered with numerous large, tuber- 

 cular elevations. 



Length -gV in. (-508 mm.). 



Hab. Hunde Islands, 25-30 fathoms (Dr. Sutherland). 



In outline and general characters this agrees closely with C. plicata as figured 

 by Reuss. The prominent tuberculation which exists in the present species, how- 

 ever, seems sufficient to give it a distinct specific rank, the only markings of the 

 typical C. plicata being described by the terms " tricostato, punctata." The species 

 referred by M. Bosquet to C. plicata, Reuss, is certainly widely different from the 

 present. 



24. Cythere rhomboidea, n. sp. (PI. LXII. fig. 5, a, h.) 



Obliquely quadrilateral, convex. Borders of the valves convex, irregularly sinuated ; 

 angles rounded. Ventral ridge sharply defined. Dorsal profile broadly ovate, with 

 subacute extremities. Surface irregularly undulated, obscurely pitted in patches. 



Length ■g'^ in. ('SI? mm.). 



Hah. Atlantic Ocean, 43 fathoms [Com. Dayman's soundings). 



The specimen from which this description is taken is probably old and worn ; but it 

 seems to be quite distinct from any hitherto described species. Its nearest relative is 

 probably Cythere triangularis, Reuss ; or rather the species figured by Professor T. 

 Rupert Jones under that name (Monog. Tert. Entom. pi. 6. fig. 5). 



25. Cythere latissima, Norman. (PI. LXII. fig. 4, a-e.) 



Cythere latissima, Norman, Nat. Hist. Trans. Northumberland and Durham, vol. i. p. 19, pi. vi. fig. 8. 

 Carapace triangular, very tumid, once and a half as long as broad. The valve 

 inclines rapidly outwards from the dorsum, forming at the ventral border a bold curved 

 ridge, which loses itself on the surface of the valve near each extremity. Anterior 

 and posterior margins produced, rounded, the latter very narrow. Dorsal margin 

 boldly arched, highest in the middle. Dorsal outline subquadrate, with produced, 

 subacute extremities. End view triangular ; sides convex ; base somewhat concave j 



