234 VIN"E: CAR-BONIFEROUS ENTOMOSTRACA, ETCf. 
unequal, irregularly ovate, sub-reniform, or sub-quadrangular, rarely 
smooth, often punctate or rugose ; anterior hinge often has an exter- 
nal tubercle over the anterior tooth. The contact margin of the 
dorsal border of each valve, has an anterior and posterior hinge 
joint without a tooth and pit, or a ridge and furrow." — Professor T. 
Rupert Jones. 
Species belonging to this genus are not numerous, and the 
specimens are very small. They are allied to undescribed forms 
found in the Carboniferous shales of Northumberland and Scotland. 
These bear MS. names by Professor T. Rupert Jones and Mr. J. 
AV. Kirkby, whose brief notes in the Transactions of the Geo. Soc, 
Glasgow, Vol. I., 1867, have enabled Mr. John Young, of the Hun- 
terian Museum, and other workers, to name their specimens. 
G. Ci'THERE CORNIGERA, Jones & Kirkby, (PL XII., Figs. 9, 9a.) 
This species may be easily recognised by the peculiar horn-like 
prolongation on the valves. In the figures, this horn-fike character 
is not so apparent as when viewed under the microscope, because in 
di'awing with the camera, these characters are not in one focus. 
Localities : Hurst, Richmond. This is a common Scottish form 
in several localities. 
7. Cythere cuneola., Jones & Kirkby, (PL XII., Figs. G, Ga, 7. ?) 
This is a common form found in the shales. In all probability, 
fig. 8, may be placed with the same species. 
Localities : Hurst, Richmond. Common in the Scottish shales. 
There are still undescribed, two, if not three species, of Ci/thera, 
which, for the present, must remain in abeyance. 
Fam. VIII. LEPERDITI^D^. 
Genus leperditia, Ronault. 
This Genus was introduced, says Professor T. Rupert Jones, and 
instituted by M. Ronault, in 1851. " Its bivalve carapace is smooth, 
convex, horny in appearance, often brownish, sub-oblong, or some- 
what semiovate in outline, longer than broad or high, inequilateral ; 
posterior half broader ; dorsal border straight, ventral border nearly 
semicircular." * This a very important genus, especially so for the 
identification in foreign localities of certain strata, and the horizons 
* Monthly Mioro. Journal, T. R. Jones, Oct. 1870. 
