Page:Quarterly Journal of the Geological Society of London, vol. 29.djvu/483

 notch ; it has, with the aforesaid tubercle, subsidiary smaller tubercles; the larger tubercle on each valve in this species appears to be truncate, and possibly the base of a spine. G. Edwardsiana occurs in the Belgian limestone, and is represented at Beith (Ayrshire), Bathgate (Linlithgowshire), and Cork (Ireland) by the variety septentrionalis. (2) C. Koninckiana has the subcentral tubercle only, with a deep nuchal furrow, apiculate end, and strongly hooked front. It is common at Cork. (3) G. obsolete, from Cork, has tubercle and furrow both faint. (4) G. Wrightii, from Cork, approaches G. cruciate, De Kon., in shape, but is easily distinguished. (5) G. quadrate, from Vise, is longer and squarer than G. cruciate, which has not been met with in the British area. (6) G. cyprelloides, from Cork, approaches the genus Cyprella either as a link or an isomorph.

Sulcuna is a new genus intended to comprise two forms in which the valves are indented with the anterior sinus and notch, and have the general outline of Cypridella Wrightii; but the dorsal edge is so deeply incised by the nuchal furrow as to have its anterior moiety raised into a slanting hump, orprocess pointing backwards and outwards. S. lepus and S. cuniculus are the two proposed species, both from the Carboniferous Limestone of Cork.

Cyprella, De Koninck (restricted) has an oval or ovate carapace, notched as in Cypridina and allied genera ; but the surface is transversely striated with parallel furrows or slight step-like markings, associated with a minute reticulate ornament. (1) C. chrysalidea, De Koninck, is long, oval, and somewhat pupa-like ; it occurs at Settle, as well as in Belgium ; but its variety subannulata, representing it at Cork, is found at Settle also ; and either the type or the variety occurs in the Isle of Man, Derbyshire, and Lintlithgowshire. (2) G. annulate (Gypridina, De Koninck, 1841), shorter and thicker than the foregoing, occurs in Belgium and at Cork, Settle, and Bathgate. All in the Mountain Limestone. The exact meaning of the details in Prof. De Koninck' s figures of Gypridella and Cyprella appears evident on the study of the large series of specimens that have now been collated.

Returning to some forms more nearly related in the shape of the carapace to Cypridina, we find a very exact analogue of Bradycinetus (B. Rankinianus) in some carapaces discovered by Dr. Rankin in a small ironstone nodule from the Lower Carboniferous shales of Gare, near Carluke. To Philomedes one form (Ph. Bairdiana) is doubtfully referable ; it is from Cork. A modification of the Cypridinal carapace is seen in two species of the new genus Rhombina, which has a subcylindrical carapace, with slanting ends, giving a rhomboidal shape to the valves, obliquely truncated at each end with parallel slopes. The antero-dorsal angle is the most prominent ; and there is a slight notch beneath it. Rh. hibernica and Rh. belgica (from Cork and Vise respectively) differ in proportion and outline.

Polycope is a recent Ostracodal genus of the Cladocopal group (Cypridina belonging to the Myodocopa), and has a suborbicular carapace without a notch, with very slight, if any, indication of the