237 



central depression in the middle of which is a roundish 

 knob ; the turns distinctly visible on the lower disc, al- 

 though neither they nor the cells are separated by sulci; 

 on the upper surface which is occupied, excepting the 

 central part, by the last turn, the cells are a little convex 

 with slight separating depressions. 0,04. Aberdeen. 



GENUS. TEXTULARIA. MACGILLIVRAY. 

 Subpyramidal, compressed, with the summit pointed, 

 the base rounded, having on each side an angular 

 or sinuous grove extending from the summit to the 

 base, and composed of two series of alternating cel- 

 lules ; the aperture semi-lunar on the inner side of 

 each cellule. 



T. OBLONG A. Macg. Aber. p. 38. Oblong lanceo- 

 late, somewhat compressed, of two alternate vertical 

 series of horizontal, rather convex, depressed, glossy, 

 somewhat tuberculated olivaceous cells. 0,04... 0,02. 

 Aberdeen. 



T. OBTUSA Macg. Aber. p. 321. Rather broadly 

 oblong, reddish white, subtruncated at the base, rounded 

 at the apex, much compressed, sloping to the margins 

 which are thin and subcarinated, ; of about sixteen al- 

 ternating cellules, disposed in two series, and horizontal, 



