1873.] JONES — BIVALVE ENTOMOSTEACA. 411 



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. Konincleiana 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. 



Stjicuna 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 Wrigldii; 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. 8. lepus and 8. cuniculus are the two proposed species, 

 both from the Carboniferous Limestone of Cork. 



Cypbella, De Koninck (restricted) has an oval or ovate carapace, 

 notched as in Gypridina and allied genera ; but the surface is trans- 

 versely striated with parallel furrows or slight step-like markings, 

 associated with a minute reticidate ornament. (1) G. clirysalidea, 

 De Koninck, is long, oval, and somewhat pupa-like ; it occurs at 

 Settle, as well as in Belgium ; but its variety subannulata, repre- 

 senting it at Cork, is found at Settle also ; and either the type or 

 the variety occurs in the Isle of Man, Derbyshire, and Lintlithgow- 

 shire. (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 mean- 

 ing of the details in Prof. De Koninck' s figures of Gypridella and 

 Cyprella appears evident on the study of the large series of speci- 

 mens that have now been collated. 



Returning to some forms more nearly related in the shape of the 

 carapace to Gypridina, we find a very exact analogue of Beadyci- 

 netus (B. Banhinianus) in some carapaces discovered by Dr. Bankin 

 in a small ironstone nodule from the Lower Carboniferous shales of 

 Gare, near Carluke. To Philomedes one form (PA. Bairdiana) is 

 doubtfully referable ; it is from Cork. A modification of the Cypri- 

 dinal carapace is seen in two species of the new genus Bhombina, 

 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. Bh. hibemica and Bh. belgica 

 (from Cork and Vise respectively) differ in proportion and outline. 



Poltcope is a recent Ostracodal genus of the Cladocopal group 

 (Gypridina belonging to the Myodocopa), and has a suborbicular 

 carapace without a notch, with very slight, if any, indication of the 



