CYPRIDELLA. 



33 



have seen. The antero-ventral margin rarely projects beyond the vertical line of the 

 notch ; it is sharper in our best specimen than in Prof. De Koninck's fig. 2 c, which has 

 it rounded in a left valve placed with the anterior edge upwards ; otherwise the outline 

 agrees with that in our fig. 4 a. The main tubercle appears rather higher up in the 

 Belgian figure than in ours ; and the ventral tubercle is not so low down, nor so large, as 

 in our figured specimen ; indeed it seems to be linear and subdivided. The sulcus is not 

 defined by Prof. De Koninck, and the edge-views of his specimen (fig. 2 a, ventral ; 2 I/, 

 dorsal) indicate only a slight transverse depression. 



Cyjiridella Edwanhiana has a profile much resembling that of Ci/pridina Cimmingii 

 (PI. II, fig. 23) ; but it is sharper behind, less deeply notched in front, sometimes more 

 produced antero-ventrally, and is not so convex, although tuberculate. 



The small specimen of Cypridella Edtoardsiana, var. sejjtentrionalis, drawn in PI. V, 

 figs. 11 a — d, is from the grey Carboniferous Limestone of West Broadstone, Beith, 

 Ayrshire ; collected by Mr. John Young. It is relatively thicker and shorter, with a 

 more angular edge-view, than figs. 4 a — c, PI. IV. The " chin " is less developed \ the 

 dorsal tubercle is wanting, but the ventral swelling is considerable, and the central 

 tubercle, quite as strong as in the Irish specimen, is truncate, as is that also ; perhaps 

 it was originally produced as a lateral spine or prickle. The posterior margin is acuminate. 

 The worn surface shows numerous, minute, scattered pits, almost quincuncially arranged. 



We have no doubt of the specific identity of the specimens alluded to. The differ- 

 ences can be only varietal at most. The features are more strongly expressed in the Irish 

 and Scotch specimens than in the Belgian figured specimen ; and the British form may 

 be recorded as Cypridella Edwardsiana, Var. septentrionalis. 



From Cork. Length \ ; height ^ ; thickness y inch. Proportions 11:8:7. 



From West Broadstone. Length ^ ; height -j^ ; thickness ^4 inch. Proportions 

 5 : 4 : 3i. 



The Belgian specimen is 5 millimetres in length. Proportions 9^ : 8 : 5^. 



The species is stated to be rare at Vise, Belgium. We have it from the Carboniferous 

 Limestone of Cork, Ireland (Mr. J. Wright, F.G.S.), and of Bathgate and West Broad- 

 stone, Scotland (Mr. W. Grossart and Mr. J. Young), and at neither place is it common. 

 The shell is preserved, but not perfectly, being minutely honeycombed by the action of 

 water, giving rise sometimes to a deceptive appearance of granulations under the 

 microscope. 



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