29O COCCONEIS. 



C. Pelta Ad. Schm. (Nordsee, pi. 3, f. 17*), plate 29, fig. 822. 



Valves small, suborbicular, the upper with rather strong costae occupying 

 about the moiety of the valve, with a hyaline area broadly lanceolate, finely 

 granular, costse 12 in 1 c.d.m. Lower valve with finer costae, 13 in 1 c.d.m., 

 raphe rather marked with central nodule coarse, rounded. Length, 2 c.d.m. 

 Breadth, 1*5 c.d.m. 



Marine. Norway. 



Group 6. EUCOCCONEIS Cleve. Valves broad or elliptic, the upper 



valve with a narrow axial area. 



( Valve with central nodule dilated into an acute stauros . . C. dirupta. 



f Valves very small, elliptic, without sulci . . C. molesta 



I 



Central 



nodule - Valves very large, broadly elliptic, the upper valve fur- 

 round, nished with broad arcuate sulci . . . C. pseudo- 



marginata. 



C. dirupta Greg. (Diat. of Clyde, pi. 1, f. 25 j H.V.H. Atl., pi. 29, 

 f- 13-15*; T)'Pe No. 247), plate 8, fig. 343. 



Valves broadly oval or elliptic, more or less flexed. Upper valve with 

 striae compact, about 15 in 1 c.d.m., radiant, finely punctuate, with puncta 

 forming longitudinal lines in zig-zag. Lower valve striate as in the upper, but 

 with striae generally interrupted by a hyaline band produced by a lateral 

 stauroneiform dilation of the central nodule. Raphe straight or gently 

 sigmoid. Length, 2 to 3*5 c.d.m. 



Marine. Found once at Antwerp' in a gathering made in the Scheldt. England, Scotland, 

 Norway. 



C. molesta Kutz ! (Bac, p. 71, pi. 7, f. 1, 2 ; h.v.h. Atl., pi. 30, 



f. 18-23*), plate 29, fig. 823. 



Valves small, elliptic, finely striate ; transverse striae about 40 in 1 c.d.m., 

 reaching to the raphe, formed of puncta, distant and consequently capable ot 

 forming longitudinal lines undulate or decussate (according to the direction ot 

 the illumination). Raphe robust ; central nodule elongated into a narrow 

 acute stauros. Length, 1*5 to 2 c.d.m. Breadth, 1 c.d.m. 



Marine. North Sea. 



Observ. The description of the above form is made from the original 

 specimen in Kutzing's collection, in which it is numbered 259. The frustules 



