OFFA. 



53 



rounded front and low-placed gape, but it is longer and much narrower anteriorly, 

 having an oval or elliptical profile. This may be a new species. 



XL OFFA.^ Genus novum. 



Carapace equivalve (?), subglobose, nearly equilateral, truncate in front, and impressed 

 by a subcentral inturning of the anterior edge of each valve, representing the Cypridinal 

 notch and equivalent to the upper gape in Entomoconchus. 



M. Barrande figures two species of Elpe from the Upper Silurian rocks (" Fauna III, 

 F, fig. 2") of Bohemia, one of which, E. inchoata, Bar., is globular, and in profile some- 

 what resembles our Carboniferous species ; but the sinuated margin is the hinge-line in 

 the Bohemian species. ('Syst. Sil. Boheme,' vol. i, Suppl., 1872, p. 511, pi. 26, figs. 

 10 a — e). E. pinguis is subreniform {pp. cit., p. 512, pi. 26, figs. 15 a — e). 



1. Offa Barrandiana. Sp. nov. Plate II, figs. 6 a — c. 



Carapace-valve subquadrilateral, boldly curved above, nearly flat below, semicircular 

 behind ; truncate in front, with a small sinus or infolding of the edges in the upper 

 third, sufficient to leave a slight fissure between the valves, as in Entomoconchis, though 

 in a less degree. 



Surface of valve smooth ; impressed by the lateral extension of the sinus obliquely 

 downwards for a short distance, and raised in a low boss a little above and in advance of 

 the centre. 



End and edge profiles long-compressed-obovate. 



Offa Barrandiana is named after the eminent geologist of Bohemia, who has eluci- 

 dated very many fossil Entomostraca. It is somewhat like Entomoconchus Scouleri junior 

 in shape, but is less convex and the gape is very different. Its valves have a slight 

 central boss, affecting the profiles of edge and end, which would otherwise be scarcely 

 gibbose. 



Length ^ ; height \ ; thickness ^ inch. Proportions 8^ : 6i : 6. . 



A grey shell in grey hmestone from Middleton, Co. Cork, Ireland. On the same 

 horizon as that of Little Island, and only a few miles distant. Collected by Mr. Joseph 

 Wright, F.G.S. 



1 Offa, a pellet. 



