

Vol. 67.] KAINOZOIC MOLLUSCA FROM CYRENAICA. 619 



II. Post-Pliocene. 



The post-Pliocene mollusca are both marine and non-marine. 

 Among the marine, which are the most numerous, are those found in 

 marls and compact limestones obtained from west of Ptolemeta and 

 the plain east of Benghazi, and considered to belong to an ancient 

 series of the post-Pliocene Period. On the other hand, there is 

 a series of shell-remains contained in a cream-coloured limestone 

 made up of comminuted shells and minutely-formed calcareous 

 pebbles, loosely, though closely, agglutinated together, occurring at 

 Benghazi, which is apparently a recent beach-deposit and much 

 younger than those limestones described as belonging to the older 

 beds of this period. In this youngest series of deposits would be 

 also included a few terrestrial shells, forming part of this collection, 

 obtained from the plain east of Derna, and Bonmansur, south of 

 Derna. The whole of the marine shells have been referred to 

 Mediterranean or Atlantic species, the terrestrial representing forms 

 now living in Mediterranean countries and chiefly those of Northern 

 Africa. 



The oldest post-Pliocene shells include chiefly Cerastoderma edule, 

 which occurs in abundance to the east of Benghazi. Similar shells 

 are known over the whole of Northern Africa and Mediterranean 

 countries generally, and, when occurring in rocks fairly well removed 

 from the sea-border, are recognized as belonging to the more ancient 

 series of this period. M. Holland has furnished a good account of 

 the occurrence of this shell in Algerian localities. 1 



The non-Marine post-Pliocene (Recent Beds) Mollusca. 



Gastropoda. 



Hygromia sordulenta (Morelet). (PI. XLIII, figs. 1 & 2.) 



Helix sordulenta Morelet, Journ. Conchyl. [Paris] 1851, vol. ii, p. 356; Le- 



tourneux & Bourguignat, Explorat. Scient. Tunisie (Prod. Mai. Terr. Fluv.) 



1887, p. 10. 

 Helicella (FruticicolaJ sordulenta Try on, ' Manual of Conchology ' 1887, 



ser. 2, vol. iii, pi. xxxix, figs. 1 & 2, p. 177. 

 Hygromia (FruticicolaJ sordulenta Pilsbry, Tryon's ' Manual of Conchology ' 



1894, ser. 2, vol. ix, p. 275. 



Remarks. — This species was originally described from Con- 

 stantine, in Algeria, and has since been recognized by Letourneux 

 & Bourguignat from localities in Tunisia. 



Occurrence. — -Associated with a reddish-brown loamy material. 



Locality. — Bonmansur, south of Derna. 



1 ' Geologie du Sahara Algerien — Chemin de Fer Transsaharien ' French 

 Government Report [Paris] 1890, pp. 158, 194, &c. & pi. xxviii, figs. 20-21. 



Q. J. G. S. No. 268. 2 u 



