88 



CARBONIFEROUS ENTOMOSTRACA. 



NOTES ON Pl. IV, Eigs. 27 and 28, and Pl. VII, Figs. 16 and 17. 



The above-mentioned figures do not belong to Cypridinads nor Cytherellids, but were 

 introduced into the Plates by inadvertence. 



1. The specimens, figs. 27 and 28 {BeyricUa gigantea) in Pl. IV, having been found 

 with the Cypridinads in the Mountain-limestone at Longnor, in Derbyshire, and at Cork, 

 in Ireland, were sketched in as associates. They are remarkable for their size. 



They have the three lobes, marginal rim, and outline of Beyrichian valves. The 

 posterior lobe is the largest (to the right hand in fig. 27, and on the left in fig. 28) as 

 usual. The middle lobe is rather larger (relatively) than in some of the known species 

 of Beyrichia ; and the three lobes are not so deeply divided by valleys as in many cases. 



Fig. 27 shows a somewhat damaged left valve inch long) in grey Upper-Carboni- 

 ferous Limestone, from Parkhill, near Longnor, Derbyshire, now in the Museum of the 

 Geological Survey at Jermyn Street, on Tablet ff . Fig. 28 is a larger, but badly 

 preserved right valve, still embedded in the light-grey Limestone of Cork, and collected 

 by Mr. Joseph Wright, F.G.S. Mr. J. R. J. Hunter has found an imperfect cast of 

 B. gigantea in the Mainpost Limestone at Braidwood, near Carluke.^ 



The relatively large size gives origin to the name that we have proposed for this 

 species. 



mm. mm. Proportions. 

 Length 4-2 5-2 . 17 21 

 Height 3-2 3-5 . 13 14 

 Thickness 3- ? . 12 ? 



Numerous specimens of a similar form, occurring on a black Lower-Carboniferous 

 shale from Eskdale, Dumfriesshire, are in the British Museum. Some have the valves 

 united, but lying open ; and in one, at least, a radiated structure of the valves much like 

 that in Cypridina radiata, Pl. V, figs. 6 d, e, /, and PJdlomedes elongata, Pl. VI, 

 figs. 1 a, b, c, is clearly indicated. The radiate structure of fossil Entomostracan 

 valves is shown also in E. 0. Ulrich's Leperditia radiata, from the Lower Silurian 

 strata (Utica Slate) near Cincinnati, Ohio, U.S. (see ' Journ. Cincin. Soc. Nat. Hist.,' 

 vol. ii, 1879, p. 2, pl. 7, figs. 2 h. This small form looks like a simple Primitia. 



2. Pl. VII, figs. 16 «, (5, c, represent a form which was at first taken for a Cytherella ; 

 but the want of dorsal overlap, and the presence of a transverse hollow, shallow as it is, 

 which in other specimens becomes a marked depression and foreshadows the sulcus seen 



1 ' Catal. Western-Scottish Fossils,' 1876, p. 71. 



