.VmE: CARBONIFEROUS ENTOMOSTRACA, ETC. 
235 
in which species have been found in this countrj^ and on the 
continent. 
8. Leperditia okeki, Munster, (PI. XII.^ Fig. 10 and lOa.) 
Cythere Okeni, Munster, Jahrbuch, f. M., 1830. 
Sotes 011 PalcRozoic Bivalved Entomofi. Jones & Kirkby, Ann. Mag. Nat, 
Hist. May, 1865, and Ibid Jany. 1875. 
It will be impossible for the student to understand this species 
and its numerous varieties without referring to these papers. The 
specimens found in the shales seem to be referable to this species. 
The authors say of this form that the CytJiere Okeni of Munster is a 
" Leperditia with the hinged or dorsal border usually a little over 
half the entire length, and the free, or ventral margin boldly rounded 
and somewhat oblique." There seems to be no other form whose 
general contour is so well marked, which has so wide a range as 
this. It is found in Russia, Xova Scotia, Germany, Belguim, and in 
the Upper and Lower Carb. strata throughout the British Isles. The 
specimens that I have are from two horizons, one set from the 
Richmond shales, and the other from the Ten Fathom Grit, Downholm, 
Yorkshire : the last was presented to me, unnamed, by the late Mr. 
Harker. There is in the shales, a small variety (PI. XII., fig. 11), 
referred to in Messrs. Jones & Kirkby's papers, which seems to have 
had a variety of names. It is magnified in the same proportions 
( X 25), as the larger specimens. There are several other varieties of 
L. Okeni given by the authors, which, are not obtainable from the 
shales supplied to me. Seeing that the L. Okeni from the Ten 
Fathom Grit are so fine and perfect, the carapaces of my specimens 
being full and unbroken, it is quite possible that other species than 
this may be found in the same horizons if local workers would give 
attention to the search. In one of their papers {Ann. Mag. Nat. Hist.y 
July, 1866, p. 9), the authors refer to a collection of Entomostraca 
submitted to them for examination by Mr. J. II. Barrow, M.A., of 
Settle, Yorkshire. It may be that other collections are still extant 
in the neighbourhood of these shales, if so, I shall be glad to hear 
of them. 
Genus Kirkbya, Jones. 
The Permian species belonging to this genus were originally 
described by Mr. T. Rupert Jones, in King's Permian Fossils, pp. 64 
