JONES.] PALAEOZOIC OSTRACODA. 71 



15. Leperditia (?) OBSCURA (sp. nov). 

 PI. 10, figs. 15 a, b, and c. 

 Leperditia, sp. nov. ? Quart. Joiirn. Geol. Soc. vol. XLVI, 1890, p. 553. 

 Length 2-7 (hinge-line 2*0), height 1-5, thickness 1-3 mm. 



Oblong and Leparditian in shape, without apparent sulcus or tubercle, 

 but with obscure indications of a ventral overlap. The ends are nearly 

 equally rounded ; ventral border gently curved ; dorsal straight, with 

 a long hinge line, and the postero-dorsal angle stronger than the front 

 angle. Surface smooth, with the convexity greatest at the anterior 

 moiety (see fig. 15 b). The ventral aspect of the carapace shows 

 along the edge of the left valve, which lies uppermost, a narrow, flat- 

 tened area, suited to receive the overlap of the right valve, as indi- 

 cated by the diagrammatic outline of the junction, fig. 15 c. The test 

 of the latter (larger) valve has disappeared, leaving only a rough and 

 somewhat crenulated cast of the interior of its overlapping edge. 



In outline this somewhat resembles the little Aparchites inatutinus, J. 

 and H., Ann. Mag. Nat. Hist., ser. 3, vol. XYI, 1865, p. 418, pi. viii, fig. 

 V, and at first sight it might, perhaps, be taken for Schmidt's Leperditia 

 Nordenskjoeldi, Miscel. Silur. Ill, 1883, p. 25, pi. 1, fig. 31, but these 

 differ in important particulars. 



The specimen under notice was collected fi"om the Trenton Lime- 

 stone (dark grey and containing Lituites undatus) at the Falls of 

 Lorette, Province of Quebec, by Mr. W. R. Billings, ne])hew of the 

 late Mr. Elkanah Billings, and an ardent palaeontologist. 



