OP THE ANTWERP CHAG. 401 



Monogr. Recent Brit. Ostrac. p. 438, pi. xsvii. figs. 27-33 (1868) ; Brady, Crosskey, and Robert- 

 son, Monog. Post-tert. Entom. Scotland, &c. p. 190, pi. vii. figs. 13-19 (1874). 



ICytherina tinnida, Reuss, Foss. Entom. osterr. Tertiar-beck. p. 57, pi. viii. fig. 29 (1850) ; Egger, 

 Ostrak. Miocan-Schicht. Orenburg, p. 17, pi. ii. fig. 11 (1858). 



?Cyiherina impressa, Reuss, Foram. u. Entom. Kreidemergeis v. Lemberg. (Haidinger's Abhandl. 

 band iv. 1850) p. 48, pi. 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 -^ inch (0-65 millim.). 



This is a widely distributed and common recent species, living usually in depths of 

 from 2 to 30 fathoms, occurrmg 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 Cythekura, 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 antennse shortly setose, 6-jointed, gradually tapering; second joint bearing a 

 rather long seta on the middle of the posterior margin; inferior antennae 5-jointed. 

 terminal claws short. Flagellum long, inarticulate. Mandibles robust, with very blunt 

 teeth. Palp 3-jointed. Branchial appendage small and bearmg only two recurved setae. 

 Terminal lobes of the first pair of maxillse long and narrow. Branchial plate bearing on 

 its external margin two non-ciliated setae, which are directed downwards and arise from 

 a separate lobe. Feet small, the terminal claws short and curved. Eyes distinct. 

 Copulative organs of male veiy 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-5 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- 



