Jones AND Kirxkpy—On Carboniferous Ostracoda from Ireland. 179 
1867. Leperditia Okeni (and Jonus & Kirxsy, Trans. Geol. Soc. Glasgow, vol. 
varieties), I yips alo, 
1875. Leperditia Okent, . Jones & Kirxsy, Ann. Mag. Nat Hist., ser. iv., vol. 
xv., p. 04, pl. vi., fig. 1. 
1880. Pr o Kirxsy, Quart. Journ. Geol. Soc., vol. xxxvi., pp. 
561, 564, 567, 573, 575, 576, 578, 588. 
1884. +5 F Jones & Kirxsy, Geol. Mag., dec. 3, vol. i., p. 356, 
pl. xi., fies 3. 
1884. by Vinr, Proc. Yorksh. Geol. Polyt. Soe., vol. viii., 
p. 235, pl. xi1., figs. 10, 10a. 
1884. i 3 Ving, The Naturalist, No. 113, p. 144. 
1885. 5 ‘3 Jones & Kirxsy, Geol. Mag., dec. 3, vol. ii., p. 540; 
1886, Quart. Journ. Geol. Soc., vol. xlii., 
p- 510; 1887, Proc. Geol. Assoc., vol. ix., 
p. 504. 
The carapaces of this important species are somewhat variable in their con- 
tour, and other features, and vary in size from 1 mm. to 3°5 mm. in length. 
Truly Leperditioid in shape, they are sub-ovate, with a straight hinge-line of 
about half the length of the valve. ‘The posterior extremity is nearly semi- 
circular, and the anterior is obliquely curved ; the ventral margin has a uniform 
gentle curve in the left (smaller) valve, but it is oblique or elliptical in the right 
(larger) valve. Hence the right valve is higher behind than the other valve, and 
more obliquely ovate ; while the postero-dorsal slope is present in each valve. 
The edge of the right valve slightly predominates along the hinge-line, and 
overlaps the other valve ventrally, more so in large specimens. 
The surface of the valves is convex or gibbose, smooth, and sometimes show- 
ing an ocular tubercle, but the muscle-spot is frequently obsolete. 
Fairly good examples of Z. Okeni, of moderate size, are present in the shales 
of the Lower Carboniferous series at Carland, but none nearly so large as those 
we have had from Holwell and Weston-super-Mare in Somerset, collected by the 
late Mr. Charles Moore, F.G.S., and as yet unpublished. 
Fig. 8 is a rather large specimen of L. Okeni from Fermanagh, among General 
Portlock’s specimens of Cypris subrecta, &c., in the Museum of Practical Geology, 
London. 
L. Okent has been found in the Carboniferous strata of Germany (Bavaria), 
Russia, Nova Scotia, in the Lower and Upper Carboniferous formations of the 
British Isles, and in the Devonian of Belgium (Givet Limestone). 
Several small forms allied to this species, if not varietal modifications, and 
indeed possibly dwarfed individuals in some instances, occur in our Carboniferous 
Shales; and although intermediate gradations often appear, they are of such 
