262 



slightly incurved hinge-line ; the anterior margin slopes with a 

 long curve round to the straight ventral edge, while the posterior 

 margin has two slopes — one ventral, and one meeting the hinge- 

 line. These five border-lines give a pentagonal aspect to the 

 valve. In the edge view the convexity of the valve is nearly 

 equal, making an acute-oval ; the end view is ovate, somewhat 

 compressed dorsally. Surface smooth, with small scattered pits. 

 Hingement as in pi. i., fig. 2. 



One specimen ; Yellow Fullers-earth Clay, Midford. 



30. CYTHERIDEA SUGILLATA,* sp. 1%. 



PI. ii., tigs. 2 a, b, c. 



Obovate in outline, almost semicircular anteriorly, more 

 convex posteriorly ; the three free margins have a broad and 

 strong rim, that on the ventral margin very nearly hidden by the 

 convexity of the valve. Surface smooth, but raised into 

 irregular wales, weals, or broken rolls in the dorsal region, and 

 into a loosely-reticulate ridge in the ventral region ; the weals 

 run together posteriorly, but their junction anteriorly is defined 

 by a small tubercle. Hingement as in pi. i., fig. 2. 



Two examples ; Blue Fullers-earth Clay, Midford. 



31. CYTHEPJDEA REFECTA, Sp. 11. 



PI. ii., figs. 3 a,b. 



A sub-oval Cytheridea, rounded at the ends, broadest posteriorly; 

 nearly straight on the ventral margin, somewhat sinuous dorsally, 

 with the anterior hinge-joint marked by a small tubercle. 

 Surface somewhat depressed and irregularly undulate, as if it 

 had been crushed and repaired — this feature, however, appears to 

 be natural. Edge view, a narrow acute-oval ; end view (not 

 drawn), acute-oval, compressed, and sinuOus. 



Two or three examples ; Blue Fullers-earth Clay, Midford, 



• . * Beaten, with weals or wales. 



