Nigerian Eocene Mollusca. 65 



size from the Eocene of Tamaske, which is probably similar to that referred 

 to by De Lapparent, possessing a ligament area nearly 100 millimetres long, 

 as well as a series of radial plications, the total height of the shell being 

 about 240 millimetres. 



COLLECTORS. Sir F. Lugard, after whom the species is named ; and 

 Sir J. Eaglesome. 



Family PLICATULID^i. 

 Plicatula polymorpha, Bellardi. 



PLATE 6, figs. 6-9. 

 Ostrea sytnmetrica. 



Bellardi: Bull. Soc. Geol. France, 1851, Ser. 2, Vol. 8, p. 261 (list name only, with no description 

 or figure). (Egypt.) 



Plicatula polymorpha. 



Bellardi: Mem. R. Acad. Sci. Torino, 1854, Ser. 2, Vol. 15, pi. 3, figs. 8-10 (non fig- n, 

 = P. bellardii, Mayer- Eymar), pp. 197, 198. (Egypt.) 



Terebratella pyramidarum. 



O. Fraas : Wiirttembergische Nat. Jahresh, 1867, Vol. 23, pi. 6, fig. 4, p. 280. (Egypt.) 



Plicatula abundans. 



Mayer-Eymar : Viertelj. Nat. Ges. Zurich, 1889, Vol. 34, p. 392. (Egypt.) 



Plicatula bovensis. 



De Gregorio : Ann. Geol. Pal. (Turin Palermo), 1894, I3th Livr., pi. 4, figs. 81, 82, p. 24. (Italy.) 

 Oppenheim "Die Priabonaschichten und ihre Fauna"; Palaeontographica, 1901, Vol. 47, pp. 142, 

 143, pi. 5, figs. 1-5. 



Plicatula pyramidarum . 



Oppenheim : Zur Kenntnis alttertiarer Faunen in Agypten ; Palaeontographica, 1903, Vol. 30, 

 part 3, p. 59. 



(?} Plicatula ? malembaensis. 



Em. Vincent : " La Faune Palcocene de Landana ; Ann. Mus. Congo Beige, 1913, Ser. 3, Vol. i, 

 p. 28, pi. 3, figs. 1-4. 



REMARKS. This species is characterised by both valves being in the possession 

 of three or four swollen radial costae which widen considerably to the base, and 

 which are divided by equally broad and prominent furrows. The shell structure 

 consists of extremely fine, close, concentric laminae of growth which are 

 crossed by numerous microscopically small radial costae, the latter being less 

 apparent and almost absent in very worn examples. This radial sculpture is 

 traceable over both valves, although it is more often seen in the furrows 

 only, where erosion would be less likely to obliterate them. The presence or 

 otherwise of radial ornamentation has created a rather long synonomy for this 



5 



