B. BuUen Newton — Egyptian Loiver Tertiary Shells. 535 



modo solidula ; valva inferiore plus minusve convexa, plerumqiie 

 umhone adnata, costis paucis, crassis, depresso-fornicatis, incequalibus, 

 postice minorihus, raro dichotomis, a lamellis concentricis, plus minusve 

 dislantihus, nodoso-spinosis ; umhone parvo, plus minusoe obtuso, leviter 

 incurvo ; cardine brevi, obliquo, canali lato ; marginibus superne 

 scrobiculato-striatis ; cicatricida musculi subtriangulari, leviter obliqua ; 

 valva superiore minore, plano-convexa, leviter lamellosa ; cardine lato, 

 piano ; marginibus superne crenulatis, inferne leviter denticulatis. 

 (Mayer-Eymar.) 



EjiMARKS. — The diagnosis here given in extenso refers to a small 

 Egyptian oyster which apparently has never been figured, but which 

 the author states is related to 0. Flemingi of D'Archiac and Haime/ 

 from the Nummulitic formation of India. Some specimens in the 

 Egyptian Collection appear to belong to this species. They are 

 smaller and narrower than the Indian species (0. Flemingi), with 

 a lower valve bearing fluted or lamellose cost^ and an upper valve 

 marked with fine imbricating concentric laminfB, besides being 

 crowded with minute vertical striations. The specimens are of one 

 nearly uniform size, and although no interiors are seen, the valves 

 being in contact, marginal denticulations are clearly displayed. 

 From the number of examples sent, this species must be fairly 

 abundant; they are slightly encrusted with ' Beekite.' 

 Dimensions. 



Height 28 mm. 



Length 17 ,, 



Diameter of united valves ... ... ... 14 ,, 



Horizons. — Middle Eocene (Mokattam Series) ; Lower Eocene 

 (Libyan Series). 



Distribution. — Egypt : El Guss Abu Said ; Nokba ; Oasis Farafrah; 

 Mons Medine Abu, near Thebes ; Mokattam — (Mayer-Eymar) ; left 

 bank of Nile about ten kilometres north of Esna. Coll. Geol. 

 Surv. Egypt (No. 1,001, Box No. 41c). 



Genus PECTEN, 0. F. Miiller. 

 Zool. Danicge Prod., 1776, p. xxxi. 

 Type. — Ostrea maxima, Linnseus. 



Peoten Mayer-Eymari, sp. nov. (PI. XIX, Figs. 9-11.) 

 Description. — Shell lenticular, circular, fan-shaped, costated ; 

 costee 20, subrotund or carinated, obsolete laterally ; grooves well 

 channelled ; surface ornamented with fine concentric lines of growth ; 

 auricles subequal. 



Dimensions. 



Height 27 mm. 



Length 27 mm. 



This species bears a true Eocene facies, being related to P. recon- 

 ditus, Solander, and P. carinatus of J. de C. Sowerby. It differs 

 from the former in the absence of any grooval squamulose orna- 

 mentation and in the possession of almost smooth sides ; from the 



^ Desc. Anim. Foss. Xummulitique I'lnde, vol. ii (1854), p. 275, pi. xxiii , 

 figs. 14, 15. 



