OF THE ANTWERP CRAG, 393 
CYTHERE POLYTREMA, noy.sp. (Plate LXVI. figs. 1 a1 d.) 
Carapace, as seen from the side, oblong, highest in front; height equal to more than 
half the length; anterior extremity broad, well rounded and bordered below the middle 
with a number of irregularly placed, rather slender, but blunt spines; posterior extre- 
mity narrower, scarcely rounded, armed with a few (4-6) downward-pointing long and 
slender spines; superior margin sloping, arched and sinuated in front of the middle ; 
inferior margin nearly straight. The outline viewed dorsally shows a central quadran- 
gular portion with two broad extremities projecting in the middle line ; width equal to 
about half the length. The lateral aspect of the valves is marked by three longitudinal 
sharply-cut ribs, one in the middle, the others just within the superior and inferior 
margins respectively ; the lower is almost straight, the other two are curved; there is 
also a curved rounded ridge just within and parallel to the anterior margin; the rest of 
the surface is occupied by large angular excavations arranged in a reticulated manner ; 
the dorsal and ventral surfaces show also longitudinal ribs, the intervals between which 
are filled with single rows of angular pits. Length 3; inch (0°98 millim.). 
Cythere polytrema occurs in moderate numbers in the two beds of the Sables infé- 
rieurs and in the Jsocardium-bed of the Sables moyens. Like the preceding, it is an 
extremely fine and well-marked species; but the valves seem usually to occur separate. 
CYTHERE SCABROPAPULOSA, Jones. (Plate LXVI. figs. 2 a, 2 0.) 
Cythere scabropapulosa, Jones, Tert. Entom. England, p. 31, pl. v. fig. 16. 
Valves, as seen laterally, oblong, subovate, higher in front than behind ; height quite 
equal to half the length; anterior extremity rounded ; posterior narrowed, rounded, and 
somewhat produced in the middle; superior margin elevated in front, then sinuated, 
and distinctly arched behind ; inferior nearly straight for the greater part of its course, 
curved upwards towards the posterior extremity. Dorsal outline oblong ovate, with 
jagged or crenate margins. The surface of the shell is closely beset with wart-like 
tubercles of considerable size ; and the anterior portion has, just within and parallel to 
its margin a row of bead-like tubercles; a prominent tubercle over the anterior hinge- 
joint. Length 3'¢ inch (0°98 millim.). 
One valve only of this species was detected, in the Pectuneulus-bed (Sables inférieurs). 
Professor Jones’s specimens were found at Bracklesham in the Middle Eocene. 
CYTHERE DAWSONI?, Brady and Crosskey. (Plate LX VI. figs. 3a, 3 0.) 
Cythere dawsoni, Brady and Crosskey, Geological Magazine, Feb. 1871, vol. viii. pl. i. figs. 5, 6. 
Carapace, seen from the side, oblong, subquadrate, highest in front. Greatest height 
equal to one half the length; anterior extremity well rounded, posterior narrower and 
not so fully rounded; dorsal and ventral margins nearly but not quite straight; the 
former with a prominence at each end. Outline as seen from above compressed, sub- 
