344 PEOF. T. R. JONES ON THE OSTEACODA 



is characterized by this elongate and shghtly tapering ohlong shape, 

 it seems advisable to take this feature and the contact-margins as 

 giving the leading characters for a separate genus Cyprmie. 



7. Ctprione Beistovii, sp. nov. (PI. YIII. figs. 27-29, and 32, im- 

 mature.) 



Length, adult 1 millim. ; immature, | millim. 



Yalves suboblong, elongate, with rounded ends, the anterior 

 rather narrower than the other. The ventral somewhat straighter 

 than the dorsal edge. The valves meet with slight ridges and fur- 

 rows. The right valve overlaps the other nearly all round, although 

 the figs. 28 and 29, being taken from odd valves, do not give this 

 impression. 



This may be the larger form, of a peapod-shape, which E. Porbes 

 referred to in his letter (to Mr. Bristow) of July 18, 1851 (see p. 314). 

 I name it after Mr. Bristow, F.E.S., F.G.iS., Director of the Geol. 

 Surv. of England, who worked so long and ardently on the Purbeck 

 strata with his friend E. Eorbes. 



Gyprione Bristovii is met with in the Upper Purbeck (specimens 

 — 40, 40 A, 40 AA, Burlston Bay ; 27, Mewps Bay, young form, 

 fig. 32, PI. YIII.) : and in the Mid-Purbeck (44 and 56, 57, 58, 

 Durlston Bay). 



It occurs in the Wealden Beds, at the Black-Horse Quarry, near 

 Hastings, and also near BexhiU, and at Lindfield, 



In Germany it is found at Obernkirchen and the Deister, as 

 shown by specimens in the British Museum. The " Cypris ohlonga " 

 of Bomer and Dunker may possibly have been intended for this and 

 D. leguminella (see above, p. 319) ; but the figures and descriptions 

 are obscure and contradictory. Certainly fig. 34, pi. 5, Monogr. 

 Eoss. Esth., Appendix, p. 128, may be a near ally of C. Bristovii', 

 but it best agrees with Romer's description of his C. ohlonga^ though 

 not with his figure. The latter is too much arched on the back for 

 G. Bristovii, and should be regarded as Gyprione ? ohlonga (Romer). 



III. Genus Metacypets, G. S. Brady, 1870. 



Metacypris, G. S. Brady, l^ature, March 10, 1870, p. 484. 



Metacypris, G. S. Brady and Robertson, Ann. & Mag. Wat. Hist. 

 ser. 4, vol. vi. July 1870, pp. 19, 20 ; Ihid. vol. ix. 1872, p. 51 ; 

 and Monogr. Post-tertiary Entom., Pal. Soc. 1874, pp. 112 and 

 116. 



Yalves subrhomboidal or suboblong, very convex ; rounded before 

 and behind, but unequally and somewhat obliquely ; rather narrower 

 and compressed in front ; dorsal and ventral margins nearly parallel, 

 but the latter turned inwards, or pressed in along the hinder half of 

 its length, so that the body of each valve swells out beyond it. 

 Hinge-line distinct, with thin flanges and narrow furrows ; but our 

 fossils do not show the details so well as the recent sjDecimens of 

 M. cordata, Ann. & Mag. IS". H. 1870, pi. 6. The right valve is larger 

 than the left. The surface is pitted in lines. 



