284 ANORTHONEIS. 



Cleve unites Orthoneis with Mastogloia. We have two species of this 



genus. 



I Valves very large, beads coarse, costal crown entirely surrounding the valve . 0. splendida. 

 ( Valves small, beads delicate, central nodule dilated into a narrow stauros . 0. binotata. 



O. splendida (Greg.) Grun, (Nov., p. 15; H.V.H. Atl., pi. 28, f. 



1-2*; Type No. 240) ; plate 29, fig. 814. 



Valve broadly elliptic, with apices obtuse rounded, narrow crown entirely 

 surrounding the valve. Raphe very robust with apices reflexed on the same 

 side, on one of the valves near the right margin, on the other near the left 

 margin. Stria; feebly radiant, about 6 in 1 c.d.m., formed of coarse beads. 

 Length, 6 to 8 c.d.m. Breadth, about 5 to 6 c.d.m. 



Marine. Lamlash Bay, Scotland (Gregory). 



O binotata Grun. (Nov., p. 15 ; H.V.H. Atl., pi. 28, f. 7* ; in Type 

 No. 243), plate 29, fig. 815. 



Valve oval, showing on each side (or more rarely on only one side) a 

 marginal semi-elliptic spot. Central nodule elongated into a narrow stauros. 

 Striae rather delicate, about T5 in 1 c.d.m. ; distinctly punctate, beads forming 

 lines, decussating lines. Length, 3-5 c.d.m. Breadth, 2*25 c.d.m. 



Marine. England. Ireland (O'Meara). Channel Islands. 



GENUS 32. ANORTHONEIS GRUN., 1868. Cleve 



Emend, 1893. 



a. b. 



Fig. 63. Anorthoneis excentrica. 

 a. Upper valve, b. Lower valve. 



Valves suborbicular, furnished with a ring unsymmetrical with 

 the longitudinal axis ; frustules with a straight sutural zone, freely 

 wandering. 



A single species. 



