Palceozoic B halved Entomostraca. 189 



10. Bythocypris acina, sp. nov. 

 (PI. VI. figs. 10 a, 10 h.) 



Proportions:— L. 11. H- 7. Th. 5. 



Carapace small, nearly ovate, but less convex below than 

 above, and contracted at one end like a grape-stone. Poste- 

 rior moiety highly arched on the dorsal and postero-dorsal 

 border. The front contracted, so as to project like the small 

 end of a pear. Left valve larger than the other. Edge view 

 oval, with sharp ends. 



Smith Coll. (two specimens) no. 52. Railway-cutting, 

 side of Severn, Ironbridge. 



11. Bythocyj)r{s phaseolus^ sp. nov. 

 (PI. Vn. figs. 11 a, 11 ^, 12 a, 12 h.) 



T> ,. / Fig. 12 : \l\ 



Proportions: I p.|^ ^^ . ^^^ 



Lens^th. Height. Thickness. 

 10 5i 



9* 7* 



Fig. 12 a is a short, high, somewhat oblong carapace, 

 arched above, almost straight below, flattish on the sides, and 

 well curved at the nearly equal ends; resembling a kidney- 

 bean. The edge view (fig. 12 h) is of a narrow, compressed, 

 subovate outline, with one end much more acute than the 

 other. Fig. 11a is more kidney-shaped than fig. 12 a, and 

 11 is fuller (thicker) than VIb] this may be a sexual if not 

 a varietal feature. 



Vine Coll. (six specimens) no. Xil. Beds no. 22 and no. 38. 

 Buildwas Beds. 



IV. Cythere, Muller, 1785. 



Valves unequal (left valve rather larger than the right), 

 oblong-ovate, subreniform, or quadrate. Surface either 

 smooth or variously ornamented. Hinge-line distinct, toothed 

 more or less strongly at its ends. 



Excepting in this last particular there are some Silurian 

 Ostracoda which would range among such Cytherce as may 

 have smooth subreniform carapaces, like Cythere'i laganella^ 

 Brady (' Challenger ' Ostrac. p. 63, pi. xvi. fig. 7). As the 

 place of the hinge-joints is distinctly shown in some of the 

 specimens before me, it may be allowed that those which have 

 a generally similar aspect and straight hinge-lines should be 

 provisionally placed in this subgroup of the genus; and thus 

 the introduction of a new generic name is avoided. In this 

 category we find : — PI. VI. figs. 5 and 6, as large forms. 



