54 Prof. T. R. Jones and Mr. J. W. Kirkby on 
genera. Beyrichia umbonata and B. striolata seem to belong 
to Kirkbya; and Bairdia levigata is a Leperditia. 
Soon after the publication of the above-named work we 
were kindly favoured by M. d’Kichwald with a series of 
Russian specimens ; and these have enabled us to arrive at 
a better understanding on some points of his Carboniferous 
species. We have also some other specimens, brought from 
Russia by the late Sir Roderick I. Murchison. Out of the 
eight species and their varieties (four) which we have identified 
among our Russian specimens, four have already been described 
as Carboniferous, two as Permian forms, one as Silurian, and 
four are new. ‘Three or four named by M. d’Eichwald we 
relegate to other authors. There remain six or seven of M. 
d’Kichwald’s Carboniferous species which we have seen in 
figures only. 
We figure the best of our Russian specimens in Plate VI. ; 
and the following observations will assist in defining the 
species, 
1 & 1*. Leperditia Okent (Von Miinster +), and var. ¢nornata 
(M‘Coy). PI. VI. figs. 1 & 2. 
Bardia levigata, var. nigrescens, D’ Kichwald, Leth. Ross. i. vii. p. 1842, 
pl. 52. fig. 5. 
This species, so common in the Carboniferous formations of 
Britain, Europe, and Nova Scotia, occurs in great numbers 
in a piece of hard, dark-grey, saccharoid limestone, labelled 
“Bairdia levigata, var. nigrescens, village of Phillineonowa, 
in the Government of Toula.” The specimens, rather small, 
are all single valves, and of a blackish colour. The general 
contour of the carapace is nearly that of the typical L. Oken?. 
The eye-spot is not distinguishable. Primitia Eichwaldi, 
Corals, and Brachiopods are associated. 
From near Likhwine, in the same Government, we have a 
minute specimen of this species, with a well-marked eye-spot 
and a slight marginal rim (fig. 2). In the former feature it 
agrees with M. d’Eichwald’s figure of his ‘“Bazrdia levigata.” 
From the same locality, in a piece of soft yellow limestone, 
other rather larger specimens occur, which we also refer to 
this species. They differ in having the carapace-valves less 
oblique than is usual with Z. Oken?, thus having a nearly 
semicircular hinder end. These might without much dif- 
culty be mistaken for a Cythere, and indeed do occur in a 
piece labelled “Batrdia excisa.” This variety is not unusual 
+ Ann. & Mag. Nat. Hist. ser. 5, vol. xv. p. 406, pl. 20. figs. 1-5. 
