•2(n', 



Mr. li. 13. Xcutoii on Fossil MoUusca dec. 



views of the oifjanism, althougli there are fraf^^meiitarj pieces 

 yieldinj^ sufficient of the median plane aspect to show the 

 recTangular nature of the chambers. This rectangular clia- 

 racter, as seen on the median plane, permits of a true generic 

 determination in favour of Ortkoi>hra(jmina, as opposed to 

 Lepidoci/cUna with rounded or hexagonal chambers, wjiich is 

 of Lower Tertiary age, and ranges from Eocene to Oligocene 

 (Priabonian) times. Judging by tlie excellent tigures of 

 Giimbel and also of Schiumberger, we may regard these 

 specimens as Michelin's prattl, which ranges from Lutetian 

 to Priabonian* and is found at Biarritz t, Kressenberg, 

 Italy, &c. For present purposes, therefore, it may be stated 

 that the limestone from Southern Nigeria belongs to the 

 Eocene series, and either to the Lutetian, Barfouiau, or 

 Priabonian division of that formation. 



A. Orthophrafpnina praffi, from Lagos, showing vertical sections. 



B. Ditto, ditto, equatorial section, showing rectangular character of tlie 



chrtUibers. 



C. Ditto, from Biarritz (for comparison). 



Locnliti/. Lagos TrDviuce of Southern Nigeria, about 14 

 miles from a spot localized as 6° 38' 30" N. lat., and ■i° 37 ' 00" 

 E. long., where the bitumen-bearing beds occur with the 

 marine MoUusca. 



* Opponht'ini, " Die Priabonaschichteu uud ihre Fauna," Bahtonto- 

 grapliica, li>00. vol. xlvii. p. 44. 



t Brever, "1 terreni Nuiunmlitici di Gassino et di Biarritz,"' Atti K. 

 Accad. Sci. Torino, 190"), vol. xli. pp. 10 li\ 



