Nigerian Eocene Mollusc a. 75 



such deposits having been variously assigned to the topmost Bartonian, although 

 more commonly placed in the Lower Oligocene (Tongrian). 



DISTRIBUTION. British : Oligocene (Headon Beds), Upper Eocene 

 (Bartonian). Europe : Eocene (throughout). Egypt : Mokattam Beds (Eocene). 



OCCURRENCE. Cuttings Nos. i, 5, 6, 10, 15. 

 COLLECTOR. Mr. Kitson. 



Family LUCINID^E. 

 Phacoides eaglesomei, sp. nov. 

 PLATE 8, figs. 18-20. 



DESCRIPTION. Shell thin, subquadrangular, compresso-convex, inaequi- 

 lateral ; anterior side short, dorsally horizontal, in the centre bluntly acuminate, 

 excavated, inner margin obliquely carinated, posterior side longest, obliquely 

 curved ; lunule small, narrow, well impressed ; escutcheon depresso-concave, 

 wide, obscurely angulated within, and at the centre ; ligament groove narrowly 

 linear, elongate ; surface covered with distant concentric more or less serrated 

 lamellae, intervening grooves finely and concentrically striated and crossed by 

 innumerable microscopical radial striations, lateral margins squamate ; umbones 

 prosogyrous, compressed, acute ; hinge plate moderately wide, depressed, with 

 a cardinal tooth, in each valve, an elongate, compressed, erect lateral on each 

 side of the right valve, posterior lateral distant, with corresponding sockets in 

 the left valve ; adductor scars elongate, anterior much produced, narrow, with 

 sometimes serrated margins, close to and nearly parallel with the pallial 

 line ; surface within pallial line roughened, irregular, punctated, beyond the 

 pallial line to outer margin the surface is radially costated, especially in older 

 or thicker specimens. 



DIMENSIONS. 



Young. Adult. 



Height ... ... ... ii ... 25 millimetres. 



Length ... ... ... 14 ... 28 



Diameter (closed valves)... 4 ... 8'5 



REMARKS. This shell is of frequent occurence in the Nigerian deposits 

 and although the valves are generally in a good state of preservation, they 



