R. BuUen Newton — Egyptian Lower Tertiary Shells. 539 



each valve ; the ligament being supported by a prominent elongate 

 nymph or fulcrum. 



Some excellent oasts of this species are in the Egyptian Collection, 

 though of course showing no dental characters such as are preserved 

 in the beautiful examples from the Bracklesham Beds of England. 

 Dimensions. 



Height 20 mm. 



Length 68 ,, 



Diameter ... 13 ,, 



Eemakks. — A very pronounced pallial sinus and some important 

 dental differences separate this genus fropa Cultelhis. It appears to 

 be rather closely related to Gari (= Psammohia) in the deep sinus 

 and character of the teeth, though possessing more inequilateral 

 valves. Such differences as are here indicated make it convenient 

 to adopt Macrosolen, proposed by Professor Mayer-Eymar in 1883 

 for the reception of S. Holloioaijsi. Professor Mayer-Eymar has 

 kindly furnished the writer with the following note on this subject : 

 " The genus Macrosolen was indeed proposed by me for Sowerby's 

 Sanguinolaria Holloioaysi, and published for the first time in the 

 work of Mr. Zittel on Egypt, 1883. I have never given a description 

 of this genus, but I think it may be a good one, taking rank in the 

 family of the Solenidge near Cultellus and Solen, having the same- 

 mode of increasing beaks and the same long ligament. In Egypt 

 the species is very common, both in the Lower and Upper Parisian 

 or Middle Eocene. I know of no other species of Macrosolen." 



The shell figured and described by Bellardi from Egypt as Solen 

 uniradiaiiis is doubtless the same as Sowerby's species ; its name is 

 therefore regarded here as a synonym of the older form. 



Horizon. — Middle Eocene (Mokattam Series). 



Distribution. — England: Bracklesham Bay; Stubbington; White 

 Cliff Bay. Egypt: between Guiset and Fayoum; Abu Zabel. Coll.. 

 Geol. Surv. Egypt (No. 644:, Box No. 60a). 



[Cast of a Luciniform Shell.] 

 Kemarks. — Cast of a small Luciniform shell showing rather 

 prominent concentric sulcations : indeterminable. 

 Horizon. — Eocene ? 



Distribution. — Egypt : Wadi Natrum. Coll. Geol. Surv. Egypt 

 (No. 639, Box No. 50a). 



Genus LITHOPHAGUS, Megerle von Miihlfeld. 

 "Entwurf Syst. Schalthiergehause" : Mag. Ges. Nat. Freund. Berlin, 

 vol. V (1811), p. 69. 

 Type. — Mytilus lithophagus, Linneeus. 

 Synonym. — Lithodomns, Cuvier, 1817. 

 Lithophagus cordatus, Lamarck. (PI. XIX, Figs. 12-14.) 

 Modiola cordata, Lamarck : Annales Mus. Hist. Nat., vol. ix (1807),. 

 pi. xviii, fig. 2 ; Hist. Nat. Anim. sans Vert., vol. vi (1819), 

 pt. 1, p. 117. Deshayes: Desc. Coq. Foss. Paris, vol. i^ 

 (1830), p. 268, pi. xxxix, figs. 17-19. 



