Vol. 67.] KAINOZOIC MOLLUSCA FROM.CY/UENAICA. 643 



Pectex akctjatus (JBrocchi). (PI. XL VI, tigs. 3-6.) 



Ostrea arcuata Broccbi, ' Conchiologia Fossile Subapennina ' 1814, vol. ii, 



pi. xiv, tig. 11 & p. 578. 

 Pecten michelotii D'Archiac, Mem. Soc. Geol. France, 1850, ser. 2, vol. iii, pt.2, 



pi. xii, figs. 20-21 & p. 435. 

 Janira fallax & deperclita Michelotti, 'Etudes sur le Miocene Inferieur de 



l'ltalie Septentrionale ' [Mem. Soc. Holl. Sci. Haarlem] 1861, pi. ix, figs. 4-7 



& pp. 78-79. 

 Pecten michelottii Schauroth, ' Verzeichniss Versteinerungen, &c.' 1865, pi. xvi, 



fig. 3 & p. 201. 

 Cardium pereziforme Schauroth, ibid. pi. xviii, fig. 9 & p. 209. 

 Pecten arcuatus Fuchs, Denkschr. K. Akad. Wissensch. Wien, 1870, vol. xxx, 



pi. x, figs. 38-40 & p. 203. 

 Janira michelottii Hermite, 'Etudes geologiques surles IlesBaleares (Majorque 



& Minorque) ' [Theses Faculte Sci. Paris] 1879, p. 223. 

 Cardium subtenui sulcatum Abich non Nyst, ' Geol. Forsch. in d. Kaukas. 



Landern : Geologie des Armenischen Hochlandes ' 1882, pi. vi, fig. 8 & 



p. 296. 

 Pecten nucalis Locard, ' Explorat. Scient. Tunisie: Descr. Moll. Tert. Inf.' 



1889, pi. x, fig. 2 & p. 51. 

 Pecten subtripartitus Locard, ibid. pi. x, figs. 4 6-4 c & p. 52 (non D'Archiac). 

 Pecten arcuatus DeGregorio, Ann. Geol. Paleont. [Palermo] 1894, pt. 13, pl.iv, 



figs. 83-85 & p. 24; Sacco, 'Moll. Terr. Terz. Piemonte' 1897, pt. 24, pi. xxi, 



figs. 14-30 (and varieties, figs. 31-36) & pp. 65-67. 

 Pecten (Janira) arcuata Oppenheim, Palaeontographica, 1900, vol. xlvii, p. 135. 

 Pecten arcuatus F. Oswald, ' Geology of Armenia ' 1906, p. 427. 



E-e marks. — Some well-marked remains of this species form 

 part of this collection, the lower or convex valve being that most 

 frequently preserved. This exhibits from twenty to twenty-two 

 costae, which are rounded, smooth at the summits, strongly curved 

 in their descent from the umbonal region, thus producing well- 

 excavated outer lateral margins, and separated by sulcations which 

 are about half the width of the ribs. Both valves possess equi- 

 distant transverse striations within the grooves which apparently 

 never extend over the summits of the eostae. 



There is only one fairly good example of an upper valve, from 

 near Bint, which shows most of the details of costal structure 

 previously referred to. It is besides very depressed, although 

 exhibiting a slightly concave surface. The auricles are small in 

 all specimens, and mostly obscure. The specimens vary slightly 

 in size, the largest example of a lower valve giving the following 



Dimensions (large lower valve): — Length = 34 millimetres; 



ight=37 mm. ; diameter = 16 mm. 



This Pecten is characteristic of the Uppermost Eocene, or that 

 part of the Lower Oligocene Beds which is regarded by Oppenheim 

 and others as Priabonian. According to Prof. Sacco, the original 

 locality of P. arcuatus should be Bocchetta Cairo of the Savona 

 district of Liguria, where Oligocene strata are known, and not 

 Rocchetta, near Asti, as given by Brocchi, where only Pliocene Beds 

 are exposed. There are many other localities for this species in 

 Northern Italy. It has also been recorded from Armenia, the 

 Balearic Islands (Majorca), Biarritz, Algeria, and Tunisia. So far 

 as Egypt is concerned, we have only a doubtful reference to its 

 occurrence in that country made by Mayer-Eymar, 1 to the effect 



i Bull. Inst. Egyptien, ser. 3, no. 6 (1896) p. 94. 



