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 areolz 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 335 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, punctato.” The species 
referred by M. Bosquet to C. plicata, Reuss, is certainly widely different from the 
present. 
24. CyTHERE RHOMBOIDEA, n. sp. (Pl. LXII. fig. 5, a, 0.) 
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 gp in. (317 mm.). 
Hab. 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. pl. 6. fig. 5). 
25. Cyruere tatissima, Norman. (PI. LXII. fig. 4, a-e.) 
Cythere latissima, Norman, Nat. Hist. Trans. Northumberland and Durham, vol. i. p. 19, pl. 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 ; 
