CYPRIDELLINA. 



25 



accompany it, of grey limestone, smaller and less globose ; and in Mr. Burrow's collection 

 from Settle is another, also less globose than our fine Belgian specimen. 



7. Cypridinella vomer, Sp. nov. Plate III, figs. 11 a — c. 



Carapace-valve obliquely subpyriform in outline ; moderately convex ; depressed and 

 produced antero-ventrally, so that the front slopes down to the straight ventral edge, 

 making a sharp prow hke a ploughshare. A narrow, distinct, almost horizontal notch, 

 cuts deeply into the upper half of the front ; the edges of the notch are slightly rimmed 

 or thickened. Edge-view of carapace acute-ovate ; end-view oval. 



Length \ ; height \ ; thickness \ inch. Proportions 11 : 7 : 5. 



A grey shell, much weathered, from the limestone of Little Island, near Cork. 

 Collected by Mr. J. Wright, E.G.S. 



III. CYPRIDELLINA. Genus novum. 



Carapace suboviform ; notched in front ; produced in the antero-ventral region ; the 

 valves locally swollen into a tubercle or circular subcentral hump above the median line. 



Prof. De Koninck in 1844 founded a genus under the name of Cypridella, typified 

 by his C. cruciata, which is a subquadrate Cypridinad with tubercular swellings on its 

 valves and a strong nuchal furrow. His Cijpridina Edwardsiana also has the furrow and 

 tubercles, although associated with the same general shape as that of the smooth 

 QjjjridineUfS above described. Thus we are led to associate the two species in one genus, 

 distinct from both Cypridina and Cypridinella, which, either among the recent species of 

 the one or those described above of both genera, very occasionally show any feature 

 analogous to the furrow or the tubercle (see Cypridina Hunteriana, PI. V, fig. 3 ; and 

 C. Brady ana, PI. II, fi!g. 13). 



We find, however, a set of Cypridinal forms corresponding in general features with 

 the smooth suboviform Cypridinella (of which we take Cypridina Zelandica, Baird, to be 

 an approximate existing type), but with the tubercle only, and without the nuchal furrow, 

 present. These want, then, an important feature present in Cypridella of De Koninck ; 

 and we now divide them off as a group under the cognate name of Cypridellina, 

 intermediate to Cypridinella (see above) and Cypridella, De Koninck, and, at the same 

 time, to some extent related to Cypridina, Milne-Edwards, 



We are aware that this distinction is in some degree artificial, and that (as before 

 intimated) the presence of either nuchal furrow or subcentral hump, in faint degree, is to 



D 



