Pahfozoic Biralced Kntomvstraca. 57 



G**. Bairdia plebeui, Reuss, var. viunda. nov. 

 PI. VI. fig. 7. 



We have one specimen of another variety of B. phbda 

 from tlie yellow limestone of Likliuine. It is rather more 

 oblong than the nsual form of the Permian B. plebeia, and its 

 posterior angle is less developed. See Reuss, " Ueber Entom." 

 &.C., Jahresb. Wetterauer Ges. 1854, p. G7, f. 5. 



7. Cy there {Potamoci/pris?) bihhata (Von Munster). 

 PI. VI. figs. 8, 9, 10. 

 Bairdia excisa (?), D'Eichwald, Leth. Ross. i. rii. p. 1342, pi. 52, f. 8. 



We have three specimens of this species from the yellow 

 limestone near Likhwine, They were sent to us by D'Eich- 

 wald labelled as '^Bairdia exa'sa.^^ They nevertheless un- 

 doubtedly belong to Von Mmisttv's "Ci/there{?) bilobata''\, 

 to which we now refer them. 



D'Eichwald's Jigures show a much greater constriction on 

 the subconcave border than we find in our specimens. 



The recent Potamocypris fidva, G. S. Brady (Ann. & Mag. 

 N. H. ser. 4, iii. pi. 18. figs. 1-4, and Nat. Hist. Transact. 

 Northumb. and Durham, iii. p. 366), presents an external ap- 

 pearance remarkably similar to that of Cythere (?) bilobata, 



8. Cytherella Murchisoniana, sp. n. PI. VI. fig. 13, a, b, 

 fig. 14, a-c. 



In a fragment of brown crystalline limestone, from a locality 

 30 wersts east of Bugulina, collected by the late Sir Roderick 

 Murchison, we have numerous specimens of a small Entom- 

 ostracan, which probably belongs to the genus Cytherella. 



It is 2V "^ch long, and half as high. The carapace-valves 

 (always separate) are oblong in outline, with the dorsal and 

 ventral borders nearly parallel ; the ends are rounded ; the 

 posterior extremity is most obtuse ; and from the region ad- 

 joining it the carapace contracts so as to give rather a wedge- 

 shaped dorsal aspect. In casts a slight constriction crosses 

 the valves near the posterior third (fig. 14, b). The shell is 

 thick, and the surface apparently smooth. 



t Ann. & Ma^. N. II. ser. 3, vol. xv. p. 409, pi. 20. f. 10. This species, 

 not uncommon in some Carboniferous rocks ot Britain and Europe, was 

 described by us {loc. cit.) as a Cythere ; it is most probably either a Pola- 

 moci/prig or a Bairdia. 



