OF THE ANTWERP CRAG. 401 
Monogr. Recent Brit. Ostrac. p. 438, pl. xxvii. figs. 27-33 (1868) ; Brady, Crosskey, and Robert- 
son, Monog. Post-tert. Entom. Scotland, &c. p. 190, pl. vii. figs. 13-19 (1874). 
? Cytherina tumida, Reuss, Foss. Entom. dsterr. Tertiiir-beck. p. 57, pl. viii. fig. 29 (1850) ; Egger, 
Ostrak. Miociin-Schicht. Orenburg, p. 17, pl. ii. fig. 11 (1858). 
? Cytherina impressa, Reuss, Foram. u. Entom. Kreidemergeis v. Lemberg. (Haidinger’s Abhandl. 
band iv. 1850) p. 48, pl. vi. fig. 5. 
Carapace of the female, as seen from the side, subsemicircular or subreniform, highest 
in the middle, height equal to more than half the length, depressed and rounded off in 
front, broadly rounded behind; superior margin boldly arched, inferior very slightly 
sinuated in front of the middle. Seen from above, broadly ovate, widest behind the 
middle, width equal to two thirds of the length, pointed in front and broadly rounded 
behind. End view subtriangular, with rounded angles and convex sides, width greater 
than height. Surface of the shell perfectly smooth. Length #5 inch (0°65 millim.). 
This is a widely distributed and common recent species, living usually in depths of 
from 2 to 30 fathoms, occurring in all parts of the North Sea and as far as Spitzbergen 
and Canada. It occurs commonly as a Post-tertiary fossil in Scotland and in Norway 
and Canada. In the Antwerp sands a few specimens only occurred in the Sables 
moyens (zone a Bryozoaires). 
Genus CytTHERuRA, G. O. Sars. 
Valves unequal and dissimilar in form, right more or less ovarlapping left on dorsal 
margin ; surface reticulated, punctated, deeply excavated or bearing irregularly-disposed 
ribs or protuberances, mostly marked with a central areola of darker colour than the 
rest of the shell; posterior extremity produced into a more or less prominent beak. 
Superior antenne shortly setose, 6-jointed, gradually tapering; second joint bearing a 
rather long seta on the middle of the posterior margin; inferior antenne 5-jointed, 
terminal claws short. Flagellum long, inarticulate. Mandibles robust, with very blunt 
teeth. Palp 3-jointed. Branchial appendage small and bearing only two recurved sete. 
Terminal lobes of the first pair of maxille long and narrow. Branchial plate bearing on 
its external margin two non-ciliated sete, which are directed downwards and arise from 
a separate lobe. Feet small, the terminal claws short and curved. LHyes distinct. 
Copulative organs of male very complex, provided with several irregular processes, and 
a very long spirally convoluted tube; usually very minute. 
CYTHERURA BROECKIANA, nov. sp. (Plate LXIX. figs. 5 a—4 d.) 
Carapace, seen laterally, suboval, highest in the middle; height equalling more than 
half the length; anterior extremity rounded ; posterior produced about the middle, but 
scarcely beaked ; dorsal margin boldly arched, somewhat flattened in the middle ; ventral 
slightly convex. Seen from above, ovate ; sides nearly parallel, tapering suddenly to the 
extremities, which are obtusely pointed; width equal to the height. End view sub- 
