206 M. Bullen Newton — Miocene 8hellsfrom Egypt. 



plications elevated, few, squaraose, irregularly radiate, and obsolete 

 near ventral region in aged examples : ligamental fossula of lower 

 valve moderately excavated and less perceptible in the upper valve. 



Dimensions (of an adult valve). — Height, 135 mm. ; length, 

 95 mm. ; diameter, 50 mm. 



. Eemarks. — Several of the present specimens are exceedingly 

 thick and coarse, whilst the ligamental areas and muscular scars 

 are of great size. Fuchs recognizes 0. pseudo-edulis and 0. excavata 

 as synonymous with 0. Virleti, the three species being somewhat 

 difficult to separate from each other. 



Horizon. — Miocene (Tortonian). 



Distribution. — Morea (Deshayes) : Eussian Armenia (Abich) ; 

 Persia (Fuchs). Egypt: Siwa and Jebel Geneflfe (Fuchs); south 

 of Middle Station. Old Suez Railway (24a); Camp 19 (13* a); 

 Camp 21 (12a). Coll. Geol. Surv. Egypt, No. 360, Box No. 12a ; 

 No. 342, Box No. 13* a ; No. 625, Box No. 24a. 



Genus PECTEN, 0. F. Miiller. 



Zool. Danicee Prod., 1776, p. ixii, 

 Ttpe. — Ostrea maxima, Linnaeus. 



PECTEN ACUTICOSTATUS, G. B. Sowerby. 

 Pecten acuticostatus, G. B. Sowerby: Quart. Journ. Geol. Soc, vol. iii (1847), p. 49, 



pi. xvii, fig. 18. 

 Janira Icevicostata, Seguenza, " Form. Tert. Eeggio (Calabria) " : Atti E.. Ac. 



Lincei, ser. in, vol. vi (1879), p. 188, pi. xiv, fig. 16. 

 Pecten ewuticostatus, Fuchs: Palaeontographica, vol. xix (1883), p. 41 (23), pi. viii 



(iii), figs. 1-6. 



Desoription. — p. testa suhorhiculari, valva altera convexa, costis 

 radiantibus 20, acutis, elevatis ; laterihus costarum interstitiisque 

 concentrice striatis ; auriculis magnis, tenuiter radiatim costatis. 

 (G. B. Sowerby.) 



Remarks. — The above constitutes the original diagnosis of this 

 species, which was drawn up from a fragmentary lower valve 

 found in the Tertiary deposits of Portugal (Tagus district). An 

 examination of the type in the Geological Society's Museum proves 

 that some valves in the Egyptian collection can with safety be 

 regarded as this species. A series of elevated triangular ribs, 

 with wide interstitial spaces ornamented by fine concentric strias, 

 appear to distinguish the shell from other forms. Similar structures 

 characterize P. loevicostata of Seguenza from Italian Pliocene 

 (Zanclean) beds, and therefore it may be included as a synonym 

 of Sowerby's older name. 



Dimensions (of largest convex valve). — Height, 70mm.; length, 

 75 mm. ; diameter, 15 mm. 



Horizon. — Miocene (Tortonian). 



Distribution. — Tagus Beds of Portugal (Sowerby); Southern 

 Italy (Seguenza). Egypt: Siwa and Geneflfe (Fuchs); Camp 

 22 (26^^^ a) and probably from Camp 21 (20a). Coll. Geol. Surv. 

 Egypt, No. 365, Box No. 20a ; No. 324, Box No. 26^^^ a. 



