Vol. 67.] KAINOZOIC MOLIUSCA FROM CYRENAICA. 627 



and is hence regarded as an Alectryonia. According to Prof. Sacco, 

 A. plicatula and its varieties range from Helvetian to the Astian 

 division of the Pliocene in Italy, etc. 



Occurrence. — In a light yellowish cream-coloured limestone, 

 associated with Operculina and Balanus cf. concavus Bronn. 



Locality. — Gubah. 



Alectryonia cf. virleti (Deshayes). 



Ostrea virleti Deshaj'es, ' Exped. Sci. Moree ' 1833, vol. iii, pt. 1 (Mollusques) 

 pi. xxi, figs. 1-6 & pp. 122-24 (—pseudoedtclis and excavata Deshayes) ; Fuchs, 

 Denkschr. K. Akad. Wissensch. Wien, 1879, vol. xli, pt. 2, pi. iv, figs. 1-9 

 & p. 106 ; Palseontographica, 1883, vol. xxx, pis. ix-x [iv-v] & p. 43 [61] . 



Alectryonia virleti K. B. Newton, Geol. Mag. 1899, p. 205. 



Eemarks. — Scattered through a limestone are some fragments of 

 an ostreiform shell, which show a regular and prominently plicated 

 ventral region producing widely flexuous margins, and resembling 

 most strongly what is present in examples of 0. virleti, a species 

 characteristic of Helvetian-Tortonian times, besides extending to 

 the Pliocene, and is found in most Mediterranean regions, such 

 as the Morea, Russian Armenia, Persia, Egypt, etc. It has quite 

 recently been recognized in the base of the Helvetian Series, near 

 Mersa Matruh (Marmarica), west of Alexandria, by M. G. F. 

 Dollfus. 1 



Occurrence. — The matrix is a cream-coloured limestone, wea- 

 thering reddish-brown. From a microscopical examination, it is 

 found to be largely composed of Orbitoides, Amphistegina, and Litho- 

 thamnion, and may therefore be regarded as of Helvetian age. Such 

 evidence, however, is against the views of the Archduke Ludwig 

 Salvator, that author having recognized the rock as of Nummulitic 

 age, a statement which makes it possible that the Amphistegince were 

 formerly included under the more general term of JVummulites. 



Locality. — The Grotto, Lethe ' River,' near Benghazi. 



Pecten zizinije Blanckenhorn. 



Pecten tournali Fuchs, Denkschr. K. Akad. Wissensch. Wien, 1878, vol. xxxviii, 



pt. 2, p. 37, non Serves. 

 Pecten solarium Fuchs, Palseontographica, 1883, vol. xxx, pp. 33, 40, & 57, 



non Lamarck. 

 Pecten solarium, var. cegyptiacus Blanckenhorn, Centralblatt Mineral. &c. 



[Stuttgart] 1900, p. 212. 

 Pecten zizinice, Blanckenhorn, Zeitschr. Deutsch. Geol. Gesellsch. 1901, vol. liii, 



p. 123, and Neues Jahrb. 1903, Beil.-Band xvii, pis. xiii-xiv & p. 167; 



Deperet & Roman, Mem. Soc. Geol. France, 1905, vol. xiii, pt. 2, No. 26, 



pi. ix, figs. 3-5 & p. 80. 



Remarks.— Only the upper valve of this shell is preserved; 

 although of imperfect condition and attached to a solid limestone- 

 matrix, it has all the essential features of the species as originally 

 described by Dr. Blanckenhorn and further remarked upon and 

 figured by MM. Deperet & Roman. It seems to possess the dorso- 

 median gibbosity which is characteristic of the species ; otherwise, 

 the valve is depressed. 



Dimensions. — Length = about 80 mm. ; height = about 70 mm. 



1 In D. E. Pachundaki's ' Contrib. Etude Geol. Marsa Matrouh ' 1907, p. 35. 



