402 E. BuUen Neioton — Egyptian Neicer Tertiary Shells. 



is nothing in this area approaching the coarse tuffs and breccias of 

 Lambay Island, and the coarse porphyry so well seen on that island 

 and occurring also at Portraine is not to be seen near Balbriggan. 



It is obvious that as we go away from Lambay Island we are 

 getting away from the great centre of eruption, and though the 

 explosive outbursts did carry ashes as far as Balbriggan, yet it was 

 not very frequently that they did so. It is also worthy of remark 

 that no trace of calcareous rocks are to be seen in the Balbriggan 

 area. The conditions requisite for the formation of such rocks 

 obtained during Middle Bala times both at Lambay and at Portraine, 

 but near Balbriggan shales and shales alone are the result of sedi- 

 mentary deposition during that period. 



V. — On some Pliocene and Post-Pliocene Shells from Egypt. 



By E. BuLLEN Newton, F.G.S. 



(PLATES XIX AND XX.) 



rilHE following notes have been drawn up from a small series of 

 JL shells belonging to the late Tertiary and Post-Tertiary forma- 

 tions of Egypt, which form part of a collection of fossils sent home 

 for determination by Captain Lyons, E.E., Director-General of the 

 Geological Survey of Egypt. 



The principal literature on this subject has been furnished by 

 Leith Adams,^ S. P. Woodward,- Oscar Fraas,^ Sir William Dawson,* 

 and Professor Edward Hull.^ To the two former we are indebted 

 for some of our earliest knowledge respecting the occurrence of 

 fluviatile shells of Post-Tertiary age at high levels in the Nile 

 Valley ; and to the remainder for valuable information on the 

 beaches and sea-beds found in the neighbourhood of the Gizeh 

 Pyramid and the Mokattam Hills, formerly regarded by Fraas as 

 of Miocene age, but which more modern observers have recognized 

 as Pliocene. 



Connected with the Quaternary history of Egypt, although not 

 of conchological interest, reference should be made to the two 

 important reports by Professor Judd ^ on the delta deposits of the 

 Nile as examined iDy a series of borings carried out under the 



1 " Notes on the Geology of a Portion of the Nile Valley north of the Second 

 Cataract in Nubia, taken chiefly with the view of inducing further Search for 

 Fluviatile Shells at High Levels"; Quart. Journ. Geol. Soc, vol. xx (1864), 

 pp. 6-18. 



* "Note on the Fresh-water Shells collected in Nubia by Dr. Leith Adams": 

 Quart. Journ. Gaol. Soc, vol. xx (1864), p. 19. 



3 " Aus dem Orient," 1867, pt. i, pp. 161-7. 



* ' ' Notes on the Geology of the Nile Valley (Raised Sea-margins ; Mokattam 

 Terraces from the Nile) " : Geol. Mag., 1884, pp. 289-292. 



* " Memoir on the Geology and Geography of Arabia Petrsea, Palestine, etc.," 

 1886, pp. 70-72. 



* First Eeport, " On a Series of Specimens of the Deposits of the Nile Delta 

 obtained by the recent Boring Operations " : Proc. Roy. Soc. London, 1886, 

 vol. xxxix, p. 213. Second Report, " On Specimens of Deposits of the Nile Delta 

 obtained by Boring Operations undertaken by the Royal Society": ibid., 1857, 

 vol. Ixi, p. 32. 



