378 CAMPYLODISCUS. 



Valve large, orbicular, with external margin broad, traversed by numerous 

 fine costa?, shortened ; costae infundibuliform, narrow portion (stem) of funnel 

 often (not always) shorter than the broader portion, the latter showing rows of 

 fine beads. Median area smooth, limited by a row of fine short lines, and 

 by the confluent apices of the costae. Diameter, 12 to 16 c.d.m. 



Marine. Coasts of England and Scotland ; in Loch Fine (Greg. !). 



C. latUS Shadb. (in T.M.S., 1854, ii., p. 16, pi. 1, f. 13; Deby, 

 pi. 3, f. 30/;*), plate 32, fig. 871. 



Differs from the preceding by its smaller size, by the broader portion of 

 the funnel being much longer than the narrow portion, and by the absence of 

 an internal circlet of puncta and of confluent apices of the costae. Diameter, 

 5 to 7 c.d.m. 



Marine. Coasts of Scotland (Greville). 



C. angularis Greg. (Diat. of Clyde, p. 30, pi. 3, f. 53; Ad. Schm. 

 Atl., pi. 18, f. 7* ; Deby Campyl, pi. 3, f. 22), plate 35, fig 909. 



Valve orbicular, of medium size ; costae not infundibuliform, very broad at 

 the margin, gently diminishing, apparently genuflexed (and appearing to 

 alternate with some shorter costae), radiant, about 5 in 1 c.d.m., leaving in the 

 middle of the valve an oval, broad, acuminate area. Diameter of valve, 

 5 to 9 c.d.m. 



Marine. Coasts of Scotland (Gregory). Bahusie (Lagerst). 



Section IV. Striata. Median area bearing distinct striae. 



Valve appearing more or less cordate, with median area smooth, limited 



by short lines ; rays funnel-shaped, with the widened portion very broad C. Thuretii. 



Valve appearing almost round, with median portion sub-quadrangular, 

 showing a second row of costae, separated from the first by a sulcus . C. bicostatus. 



C. Thuretii Breb. (Diat. Cherb., pi. i, f. 3; h.v.h., pi. 77, f. 



1* ; Types Nos. 438 and 439), plate 14, fig. 595. 



Valve appearing irregularly circular or broadly ovoid, with coarse robust 

 costae, 2 to 3 in 1 c.d.m., becoming abruptly narrower near the central portion 

 of the valve, which is covered with delicate transverse striae, about 10 in 1 

 c.d.m., interrupted by the pseudo-raphe on each side, at a short distance from 

 the latter, by a sulcus parallel to it. General appearance of the valve smaller 

 to that of Surirella fastuosa. Diameter, about 5 c.d.m. 



Marine. Rare. Blankenberghe. Washings of mussels (Debv), Coasts of England (W. Sm., 

 Gregory), France (Br6b. Thuret,), Bahnsie (Lagerstedt). 



