232 



white, rather glossy, opaque, faintly and longitudinally 

 rugose whorls, outer margins thin but no carinate ; all 

 the turns apparent on both sides, the last very large ; 

 mouth large, obovate-oblong, with a slightly thickened 

 and somewhat spreading margin and a medial erect 

 tooth extending to two thirds its height and enlarged 

 and emarginated at the end. 0,08. Aberdeen. 



SPIROLOCULINA. MACGILLIVRAY. 

 Suborbicular, depressed, with the cells curved and op- 

 posed to each other in a single plane, and completely 

 exposed or not embracing each other ; the aperture 

 roundish at one end of the last turn. 



S. CONCENTRICA. Macff. Aberd. p. 36. MILIOLA. 

 C. Brown III. t.\.f. 22. Elliptic-orbicular, concave 

 on both sides, very thin, of about five opposite arcuated 

 cells distinctly separated by a groove ; outer cells exter- 

 nally flattened or slightly convex ; white generally with 

 two brown or blackish streaks on each turn ; aperture 

 nearly square with an erect tooth-iike process and thick 

 brown margin. 0,04. Aberdeen. 



ARETHUSA.MoNTFORT. 



Cells arranged obliquely and alternately along an axis. 

 with the moutJis of all the chambers having an aspect 



