388 DR. G. 8S. BRADY ON THE OSTRACODA 
Carapace somewhat peachstone-shaped: viewed from the side, it is highest in the 
middle, the height being equal to two thirds of the length; anterior extremity well 
rounded and broad, posterior narrower and produced into a short almost obsolete beak ; 
dorsal margin strongly arched, inferior slightly sinuated in the middle. Seen from 
above, the outline is ovate, widest in the middle and tapering evenly to the pointed 
extremities; width equal to half the length. End view broadly ovate, narrowed above 
and broadly rounded below. The valves are very convex, and are marked all over the 
surface with rather coarse and closely-set circular punctures. Length 3; inch (0°66 
millim.). 
C. cicatricosa has been found in some of the Tertiary deposits of France and Germany, 
associated with the preceding species; also in some English Post-tertiary deposits. I 
do not know of its existence in the living state at the present day, unless it be consi- 
dered identical with C. convera, Baird, to which species I must suppose that the remarks 
of M. Bosquet probably refer when he speaks of its being found on the coast of Italy. 
Our figure and description are drawn from a specimen found in the Sables moyens 
d’Anvers (zone 4 Bryozoaires). 
CYTHERE @DICHILUS, noy. sp. (Pl. LXIV. figs. 1 a-1d.) 
Carapace, as seen from the side, subquadrangular, rather higher in front than behind ; 
height equal to nearly two thirds of the length; anterior margin well rounded ; poste- 
rior angularly produced below, rounded off obliquely above ; dorsal margin sinuated in 
front of the middle; ventral evenly and rather strongly convex. Viewed from above, 
the shell is broadly ovate, tapering evenly to the extremities, both of which form 
broadly mucronate projections; the width in the middle is equal to half the length. 
End view irregularly and broadly ovate, narrowed towards the apex. The margins of 
the shell are much produced, rounded and swollen; just within the ventral border is a 
very conspicuous, thick, and rounded ridge, and near the centre of the valve a large, 
smooth, rounded tubercle; the rest of the surface is marked with rounded pittings, 
which are arranged in transverse rows. ‘The hinge-line on the dorsal aspect is marked 
by a longitudinal furrow; the ventral surface shows the strongly developed marginal 
plates of the shell with an intervening depression. Length 34 inch (0°75 millim.). 
This species occurs in all the three divisions of the group, inférieurs (Pectunculus- 
bed), moyens (zone a Bryozoaires), supérieurs (Zrophon-bed). 
CYTHERE PETROSA, nov. sp. (Plate LXIV. figs. 5 a—5 d.) 
Carapace tumid, wedge-shaped: seen from the side, subquadrangular ; height nearly 
uniform throughout, and equal to rather more than half the length; extremities equal 
and obliquely rounded ; dorsal and ventral margins parallel and almost perfectly straight, 
the dorsal being much the shorter of the two. Seen from above, the outline is ovate, 
very tumid behind, the greatest width being fully equal to the height, narrowed and 
