Vol. 67.] KAINOZOIC MOLLUSCA FRO.U CYRENAICA. (547 



imbricating sculpture strongly resembling that present in Dr. 

 Oppenheim's TracJu/cardium yranconense, a Priabonian species 

 from the Venetian Alps. 



The specimen is much weathered, so that the ornamentation is 

 strongest in the grooves, and it is only very obscurely and occa- 

 sionally seen to pass over the ribs themselves, which through 

 erosion are mostly smooth at the summits. 



Dimensions (left valve). — Length = 42 millimetres ; height = 

 (about) 42 mm.; diameter=13 mm. 



Occurrence. — In a hard cream-coloured limestone weathering 

 to a reddish tint and containing Nummulites. 



Locality. — Mersa Susa. 



Lucina cf. pharaonis Bellardi. 



Lucina pliaraonis Bellardi, Mem. R. Accad. Sc. Torino, ser. 2, vol. xv (1854-55) 

 pi. ii, fig. 12 & p. 190 ; Oppenheim, Palseontographica, 1903, vol. xxx. pt. 3, 

 No. 1, pi. xiii, figs. 1-2, pi. xv, fig. 6 & p. 124. 



Remarks. — There are several casts of a luciniform shell which 

 in general aspects show relationship to Bellardi's L. pliaraonis, 

 from the Mokattam Beds of Egypt. They present the same sub- 

 orbicular contour ; the valves are also fairly well inflated, and 

 mostly exhibit the postero-dorsal compression as well as a nearly 

 horizontal antero-dorsal line immediately below the umbones. 

 Obscure muscular and other markings are seen on the surfaces, 

 although generally much too indistinct for definition ; occasionally, 

 concentric striations are preserved. The largest example shows 

 the following measurements : — 



Dimensions (with closed valves): — Length=51 millimetres; 

 height = 47 mm. ; diameter=30 mm. 



According to Dr. P. Oppenheim, the species is restricted to Egypt 

 and Algeria, Coquand's l L. moevusi from the latter region being now 

 recognized as the same shell. The species ranges throughout the 

 Mokattam Beds of Egypt ; but, in Algeria, it is said to occur in 

 the Suessonian stage of the Eocene deposits. 



Occurrence. — Specimens mostly in a cream-coloured limestone 

 weathering to various reddish tints, and sometimes associated with 

 Nummulites. 



Localities. — Top of pass leaving Wadi Khumas ; two hours 

 before reaching the shrine of Sidi Mahomed (before Slonta) ; Merj 

 Wells ; Kuff Narbea, north of Wadi Eiryah. 



Lucina cf. nokbaensis Oppenheim. 



Lucina nokbaensis Oppenheim, Palaeontographica, 1903, vol. xxx, pt. 3, No. 1 

 pi. x, fig. 13 & p. 139. 



Remarks. — The specimen thought to be related to this species 

 is an internal cast, with united valves of fairly large size and 

 of moderate convexity. Its contour, however, is rounded, and 



1 ' Geologie & Paleontologie de la Eegion Sud de la Province de Con- 

 stantine ' 1862, p. 269 & pi. xxx, figs. 17-18. 



