288 COCCONEIS. 



4 or 5 longitudinal lines. Valve bordered with a row of much finer puncta, 

 8 in i c.d.m. Length, about 5 c.d.m. Breadth, up to 4 c.d.m. 



Marine. Scotland, Ireland (O'Meara), Bahusie. 



aa. Valves with delicate puncta. 



C. Pediculus Ehr. (In Kutz. Baa, pi. 5, f. IX. i. ; H.V.H. Atl., 

 pi. 30, f. 28-30* ; Types Nos. 248, 249), plate 8, fig. 340. 



Valve elliptic, plane or very slightly flexed.; median hyaline zone of the 

 upper valve enlarged at the centre of the valve, and showing feeble traces of 

 raphe and nodules ; lower valve furnished with a ring covered with striae, 

 punctate, distant, about 15 in 1 c.d.m., separated by a hyaline zone from the 

 rest of the valve, which is covered with radiating striae, fine, punctate, about 

 22 in 1 c.d.m. Length, 1-25 to 3*5 c.d.m. 



Fresh and brackish water. Common everywhere. 



C. Placentula Ehr. (Amer., I.,- i., 10, 24; H.V.H. Atl., pi. 30, 

 f. 26 and 27*; in Types Xos. in, 190, 206, 259, etc.), plate 8, fig. 341. 



Valve elliptic, plain or very slightly flexed ; median hyaline zone of the 

 superior valve enlarged at the centre of the valve, and showing feeble traces 

 of raphe and nodules ; inferior valve furnished with an annulus covered with 

 striae, punctate, distant, about 15 in 1 c.d.m., separated by a hyaline zone from 

 the remainder of the valve, which is covered with radiating striae, very fine, 

 punctate, about 22 in 1 c.d.m. Length, from 1/25 to 3*5 c.d.m. 



Fresh and brackish water. Common everywhere. 



var. lineata. (C. lineaia; tl.V.H. Atl., pi. 30, f. 31 and 32*; Type 

 No. 250), plate 8, fig. 342. 



Differs from the preceding, from which it is not specifically separable, 

 by its much larger size and by the striae of the upper valve, the puncta 

 of which form longitudinal lines in zig-zag. Striae of lower valve about 

 17 in 1 c.d.m. Length about 7 c.d.m. 



Brackish water. Rare? Antwerp, Blankenberghe. 



** Valve without a separable marginal ring. 



a. Upper valve furnished with costae. 

 Group 3. DISCONEIS Cl. Valve elliptic. 

 C. pinnata Greg. (Q.j.m.s., 1859, vii., p. 79, pi. 6, f. . ; H.V.H. 



Atl., pi. 30, f. 6 and 7*;; plate 29, fig. 818. 



