400 DE. O. S. BEADY ON THE OSTEACODA 



Found rather sparingly in both beds of the Sables inferieurs, and also in the zone a 

 Isocardium coi- (Sables moyens). 



LoxocoNCHA VAEiOLATA, nov. sp. (Plate LXVIII. figs. 4 «-4 d.) 

 ?Cythere subtriangularis, Speyer, Ostracoden der Casseler Tertiarbild. p. 26, pi. ii. fig. 6. 



Carapace, as seen from the side, oblong, subrhomboidal ; anterior and posterior 

 extremities almost exactly alike, rounded below and bevelled oif above the midiUe ; 

 dorsal margin straight, ventral convex and slightly sinuated in front ; height equal to 

 more than half the length. Seen from above, ovate, tapering rather suddenly to the 

 extremities, which are sharply mucronate ; width about equal to the height. End view 

 subquadrate, somewhat narrowed and rounded off at the apex. Shell-surface marked 

 by rather large polygonal excavations, which tend to run in longitudinal rows, especially 

 towards the anterior margin and on the ventral surface. Behind the middle of the 

 ventral margin the valves are produced into a distinct but not very prominent angulated 

 alseform ridge. This, however, is absent or obsolete in some specimens, which seem 

 to belong to this species, as they agree with it in other respects. Length -^ inch 

 (0-66 millim.). 



This species may very possibly be identical with Cythere subtriangularis, Speyer, the 

 figures of which agree almost entirely with it, except in the absence of any angulated 

 ridge ; for the present, however, I prefer to consider it as distinct. Cythere hastata, as 

 figured by Egger and (more doubtfully) by Eeuss, are also either the same or nearly 

 allied forms ; without examination of authentic specimens it is impossible to pronounce 

 with certainty. Lastly, the species described by myself {Loxoconcha angustata and 

 L. alata) are both nearly allied but distinct, as also is L. multifora (Norman). 



L. variolata has been found pretty plentifully in the Pectunculus-hed and in the zone 

 a Bryozoaires, and less abundantly in the Panopcea-menardi bed (Edeghem and Kiel). 



Genus Xestoleberis, G. O. Sars. 

 Shell smooth and polished, ornamented with small, round, distant papillae, much 

 lower in front than behind, in t\ie fmnale very tumid behind; hinge-joint formed by 

 a dentated projecting crest of the left, which is received into an excavation of the right 

 valve ; ventral margin of both valves incurved in front of the middle. Upper antennae 

 6-jointed, the last four joints successively decreasing in length and bearing very short 

 simple setae ; lower antennae short, 4-jointed. Flagellum of moderate length. Mandible- 

 palp 4-jointed. Branchial appendage small and bearing only two setae. Maxillae as in 

 Loxoconcha. Feet short. Postabdominal lobes bearing two setae. Eyes distinct. Ova 

 and immature young borne within the shell of the female. 



Xestoleberis depressa, Sars. (Plate LXVI. figs. 8 a-8 d.) 

 Xestoleberis depressa, G. O. Sars, Oversigt af Norges marine Ostracoder, p. 68 (1865) ; Brady, 



