190 Mr. C. Meresclikowsky on Sellaphora. 



Sellaphora elliptica, sp. n. (PI. IV. figs. 13-16.) 



Valve elliptical to liuear-ellipticul, with subcuneatc ends ; 

 terminal nodules distant; median line accompanied by a 

 narrow dark space, broadening towards the centre, repre- 

 senting probably the axial area ; stria3 tine. Frustule very 

 narrow, linear, with rounded angles. Length 0'0I2-0'024:5 

 mm., breadth of valve 0*00()-0'001) mm., breadth of girdle- 

 face 0-G036-0-0055 mm. 



Marine: San Pedro (California). 



This species is easily distinguisiied from the preceding one 

 by the form of the valve, which is much broader, elliptical, 

 in larger forms almost linear (Hg. 15) ; towards the ends the 

 valves are always a little cuneate. The frustule is usually 

 very narrow. 



The endoehrome is of the same type as in the two pre- 

 ceding species ; the median portion is narrow, often asym- 

 metrical, being broader on one side (tig. 15) and not thicker 

 than the four prolongations. The latter are usually more or 

 less short, only rarely attaining the summit of the frustule 

 as in fig. 15. The zonal prolongations are much broader 

 than in S. jBorsgoicii; sometimes they cover the entire 

 surface of the connecting-zone (fig. 14), but as a rule they do 

 not reach the ventral side (fig. IG). Colour of endoehrome 

 yellow-brown, of a more or less dark tint. Pyrenoi<ls absent. 

 Elaioplasts usually two in number, variable as to their dispo- 

 sition, either at the extremities of the prolongations and 

 along their median line or nearer to the centre (figs. 15, 16); 

 they are never free, i. e. of the kind which I call libroplasts. 



This is a free-living species ; its movements are rather 

 fast, proceeding in a straight line with continuous fluctuations. 

 It is not rarely to be met in a laguna at Long Beach, near 

 8an Pedro (California), where the water is usually quite 

 saline; in winter time when it rains (which seldom iiappens 

 in California) the water becomes of course a little brackish 

 for a while. 



Sellaphora (?) hacilliformis (Grun.), ^ler. 

 (PI. IV. tig. 17.) 



Nuxxida laciniforviis, firun., Cleve & fJruiiow, Arrt. Dint. 18^0, p. 44, 

 pi. ii. fig. 51 ; \an Ilfuick, .Synop.s. pi. .\iii. lig. 11 ; I'antucksek, iii. 

 pi. iii. fig. 4'J. 



I give the figure of a valve of this .species after Grunow 

 (Arct. Diat. pi. ii. fig. 51). V^lien compared with fig. 5, 

 representing a valve of S. jmpula, one can easily see the 



