78 R. BULLEN NEWTON on 



more compressed valves, smaller and rather depressed umbones instead of 

 being swollen ; it has besides a straighter ventral border, more vertical sides, 

 and a nearly rhomboidal contour which is a marked feature of the shell. 

 Again, the notched character at the base of the dorsal areas appears to be 

 obsolete in the Egyptian species, that form presenting an almost even outline. 

 Either under Phacoides or Fischer's 1 Dentilucina, which is its synonym as 

 first pointed out by Dr. Dall, 2 several species of this genus have been 

 recognised by M. Cossmann 3 from the Eocene and Miocene rocks of France, 

 as also by Dr. Sacco 4 from the Oligocene and later Tertiaries of Italy ; 

 many species have also been reported from the United States and West 

 Indian Tertiaries by Dall, 5 but these are all of much rounder contour and 

 very often possessing deeper and more bombiform valves. The Nigerian 

 shell differs, also, from Phacoides eaglesormi found in the same deposits, on 

 account of its less compressed valves being of different contour, and the strong 

 differences existing in connection with the sculpture characters. 



OCCURRENCE. Cutting No. 6. 

 COLLECTOR. Mr. Kitson. 



Divaricella oppenheimi, sp. nov. 

 PLATE 7, figs. 2, 3. 



DESCRIPTION. Shell (left valves) small, sub-globose, robust, equilateral, 

 convex, postero-dorsal margin obliquely curved, antero-dorsal truncated, lateral 

 and ventral hemi-spherical ; ligament cavity narrowly elongate ; lunule small, 

 wide, well excavated ; umbones median, small, obtuse ; hinge line arched 

 posteriorly and obliquely curved anteriorly, strong, with two short, divergent 

 cardinal teeth, anterior thickest, separated by a small triangular socket to 

 receive the single tooth of the other valve, a prominent socket on each side for 

 the reception of the lateral teeth of the opposing valve, posterior furthest from 

 the umbo ; anterior adductor scar narrowly lingulate, obliquely directed down- 



1 Manuel de Conchyliologie, 1887, p. 1143. 



2 Proc. United States Nat. Mus., 1901, Vol. 23, p. 805. 



8 Ann. Soc. R. Mai. Belgique, 1887, Vol. 22, p. 36; Inconog. Coq. Foss. Eocene Paris, 1904, Vol. I, 

 Fasc. 2, pis. 23-26 ; Act. Soc. Linn. Bordeaux, 1911, Vol 65, pp. 304, 309-327. 



4 Molluschi Terz. Piemonte, 1901, Vol. 29, pp. 78-89. 



i Trans. Wagner Free Inst. Sci., Philadelphia, 1903, Vol. 3, pp. 1359-1385. 



