R. Bullen Newton — Egyptian Neicer Tertiary Shells. 403 



auspices of the Eoyal Society to ascertain at what depth the solid 

 rock might be reached, a result unfortunately not achieved, for after 

 piercing the alluvial beds to a depth of 84:5 feet from the surface 

 and 319 feet below sea-level at Zagazig, operations were suspended 

 without meeting with the basal formation. The first of these 

 reports deals with the mineral and chemical nature of the deposits, 

 whilst the other includes some information upon the Foraminifera. 



MOLLUSCA: GASTEROPODA. 



Genus PLANOEBIS, Geoffrey. 

 Traite Coq. FIuv. Terr. Paris, 1767, pp. 12, 81. 



Type. — Helix cornea, Linnasus. 



Planorbis Pfeifferi, F. Krauss. (PI. XIX, Figs. 6-8.) 

 Planorhis Pfeiferi, Krauss : Die Siidafrikanischen Mollusken, 1848, 

 p.*83, pi. V, fig. 7. 



Description. — P. testa cornea, nitida, diapJiana, oblique striata, 

 ntrimque {supra prof undius) concava, umbiiicata ; anfractibus 5 con- 

 vexis, mediocriter crescentibus, idtimo supra convexiuscido, infra 

 inflnto, i totius diametri cequantce ; suturis profundis ; apertura 

 lunato-rotimda ; peristomate simplice. (Krauss.) — The shell is 

 concave on both sides, though more so umbilically; it possesses 

 from four to five convex whorls, the last one increasing very 

 rapidly in width; suture deep; aperture roundly lunate; peristome 

 simple ; test obliquely striated. 



Dimensions. — Diameter, 10 mm. ; height, 4 mm. 



Remarks. — A careful comparison has been made with recent 

 examples of this species in the Zoological Department of the British 

 Museum, the present Egyptian shells being found identical in every 

 character. A Peruvian shell, P. trigyrus of Philippi,^ appears to be 

 closely related, though differing in its more orbicular aperture and 

 lesser diameter. Another form, P. Sudanicaniis, E. v. Martens,* is 

 separated by its more convolute spiral system, a smaller umbilical 

 area, and less lenticular shape. 



Horizon. — Post-Pliocene (Lacustrine or Fluviatile Deposits). 



Distribution. — Natal: Umgani Valley (Krauss). Egypt: near 

 Farshut, Nile Valley. Coll. Geol. Surv. Egypt (No. 1,040, Box 

 No. 52c). 



Genus MELANIA, Lamarck. 

 Mem. Soc. Hist. Nat. Paris, 1799, p. 75. 

 TyPE. — Helix amarula, Linnaeus. 



Melania tuberculata, Midler. (PI. XIX, Figs. 9-11.) 

 Nerita tuberculata, 0. F. Miiller : Verm. Terrest. Fluv. Testaceorum, 

 vol. ii (1774), No. 378, p. 191. 



* Malakozoologische Blatter, vol. xvi (1869), p. 39 ; Novitates Concliologicae, 

 Tol. iv (1870), p. 25, pi. cxiv, figs. 13-16. 



2 Malakozoologische Blatter, vol. xvii (1870), p. 35; Novitates Concliologicae, 

 vol. iv (1870), p. 23, pi. cxiv, figs. 6-9. 



