POTAMOCYPRIS. 



11 



Among other characters it has rather thick valves, and the right is larger than 

 the left valve. 



1. PoTAMOCYPRis TRiGONALiSj et var. L^vis {Cytheriileis, Jones, 1856). 



Cytiieeideis teiqonalis, et var. L^via, Jones. Moiiogr. Tert. Entom., 1857, 



p. 47, pi. ii, figs. 2 a — h. 

 PoTAMocYPRis — — Jones ^ Sherborn. Geol. Mag., 1887, 



p. 58G. 



Besides those mentioned in the ' Monogr. Tert. Bntom.,' we have two 

 examples of this species from Mr. Clement Reid's collection, — one from the 

 Norwich Crag at Bramerton, — and one from the Wej'bourn Crag at Bast Runton.^ 

 'I'he latter specimen is the large and smooth form distinguished as var. l^vis. 

 (Brit. Mus. and Mus. Pract. Geoh) 



2. PoTAMOCYPRis TOBERCULATA (Gytherideis, Jones, ' Monogr. Tert. Bntom.,' 1856, 



p. 47), from the Crag of SufPolk and Bssex, is also to be noted as belonging 

 to this genus. (British Museum.) 



3. PoTAMOCTPRis Brodiei, sj>. nov. Woodcut, Fig. 1. 



Fio. 1. — Potamocypris Brodiei, ep. nov. a. Eight valve (pliglitly broken at the posterior margin). 



b. Edge view. Magnified 20 diameters. 



This very neat subtriangular valve, 1 mm. long, cream-coloured, and polished, 

 is delicately punctate with exquisitely fine pittings. It is related to the recent 



1 Mr. Clement Reid, F.Gr.S., has given a detailed account of the Norfolk deposits in the ' Mem. 

 Geol. Survey : The Geology of the Country around Cromer,' 1882. The Weybourn Crag is 

 described at pp. 11 — 19; and the Entomostraca from that deposit are mentioned at p. 66. See also 

 Prof. Prestwieh's " Memoir on the Crag Beds of Suffolk and Norfolk," ' Quart. Journ. Geol. Soe.,' 

 vol. xxvii, p. 457, 460, &c. ; and H. B. Woodward's ' Geology of England and Wales,' 2nd edit., 

 pp. 465 — 474, for Bramerton, Weybourn, &e. The Bramerton Crag is also treated of in H. B. 

 Woodward's ' Geol. Surv. Mem. : The Geology of the Country around Norwich,' 1881, pp. 33 — 55, 

 82, &c. The list of Ostracoda from Weybourn referred to above does not agree with our determina- 

 tion in all respects. Thus we have not found Cythere tuberculata, Sars, nor C pellucida, Baird, 

 among the specimens we have seen ; and probably C. concinna, Jones, is represented by the set of the 

 closely allied C. anyulata, Sars, which we have met with. Other species in our series are not 

 indicated in the printed list referred to. 



