190 MR. R. B. NEWTON OX NOW- MARINE MOLIXSCAN [June I9T4, 



Occurring with these specimens are a number of isolated 

 opercula of large, thick, and robust character, and, moreover, of 

 calcareous structure. Only one fragmentaiy example is observed 

 to be more or less in situ, covering the broken aperture of one of 

 the smaller forms of this species. 



Dimensions in millimetres: — 



q, ,, J Height varying from 18 to 45. 



[Diameter (maximum) varying from 15 to 45. 



n , /Height =33. 



°P erculum {width=20. 



Distribution. — Although there are no records of the existence 

 of this species in the waters of Birket el Qurun, it occurs in the late 

 post-Pliocene deposits of that district of Egypt (examples are pre- 

 served in the British Museum and in the Cairo Museum). Besides 

 the original locality of Lake Mareotis, this mollusc has been found 

 in the region of the White Nile, the Victoria Nyanza, Lakes Tan- 

 ganyika and Nyasa, as well as in parts of Portuguese West Africa. 



Occurrence. — The specimens were mostly discovered in Beds 

 14 & 15, associated with remains of Chelonia, Crocodilia, and 

 Lanistes carinatus. More isolated examples are represented from 

 the following beds : — 



Bed 16. Opercula only — associated with Hyracoid, Crocodilian, 

 and Chelonian remains and Cleopatra. 



j, 1 -1 q [ Accompanying Chelonia and Crocodilia. 



Bed 21. With Lanistes carinatus, and vertebrates similar to 

 those found in Bed 17. 



Bed 24. Opercula only — with Dinotherium and other verte- 

 brates. 



Bed 31. With Dinotherium and other vertebrates. 



Bed 32. With Lanistes carinatus and Cleopatra. 



Bed 34. An isolated cast in brown marlstone. 



Localities.— Nira (Beds 14, 15, 19, 24, 31, 32, 34) ; Kachuku 

 (Beds 14, 15, 16, 17, 21, 24) ; Kikongo (Bed 14). 



Lanistes carinatus (Olivier). (PI. XXX, figs. 5-7.) 



Helix terrestris bolteniana contraria Chemnitz, ' Conchylien-Cabinet ' vol. ix 



(1786) p. 89 & pi. cix, figs. 921-922. 

 Ampullaria carinata Olivier ' Voy. Emp. Othoman, Egypte, Perse ' 1804 (An 12) 



vol. iii, pi. xxxi, fig. 2 & pp. 67, 68. 

 Lanistes olivieri Montfort, ' Conch yliologie Systematique ' vol. ii (1810) p. 123 



(= carinatus Olivier). 

 Lanistes carinatus E. von Martens, ' Beschalte Weichthiere Ost-Afrikas — 



Deutsch-Ost-Afrika' (K. Mobins) vol. iv (1898) p. 169. 

 Meladomus (Lanistes) carinatus Kobelt, Kuster's ' Conchyl.-Cabinet ' pt. 550 



(1911) p. 19. 

 Lanistes carinatus K. B. Newton, Proc. Malac. Soc. London, vol. x (1912) p. 75. 



Remarks. — The principal characters of this species are well 

 epitomized in Olivier's diagnosis of 1804: — 'Ampullaria cari- 

 nata: sinistra, depresso-turhinata ; umbilici maximi inargine 

 carinato ; apertura suborbicidata.^ For the more modern inter- 



