15 



(gradually enlarging from the beaks to the opposite extremity) but the 

 concentric markings on the casts induce me to believe that, it does not 

 belong to that genus. 



West end of the island ; H. R. J. Richardson, T. C. Weston. 



C ? UNQULATA, n. sp. — Obliquely ovate, cordiform, extremely tumid ; 

 anterior extremity short rounded ; ventral margin rather strongly and 

 uniformely convex ; posterior extremity sub-angular about the mid-height, 

 obscurely rounded above. The beaks are long and much incurved, but 

 not in contact. The greatest gibbosity is a little in front of the middle. 

 From the beaks the principal convexity extends with a somewhat sigmoid 

 curve backwards and downwards towards the lower posterior margin. 

 Surface with a number of concentric sub-lamellose ridges of growth 

 which leave their impressions on the cast of the interior. Length 19 

 lines ; height 14 lines ; depth of both valves 15 lines. In a dorsal or 

 ventral view the outline is broadly cordiform, the beaks turning forward 

 and downwards with a hook-shaped curve. The space between the beaks 

 (in the only specimen collected) is obscured by the matrix so that the 

 characters of the hinge line cannot be ascertained. 



Macasty Bay ; H. R. T. C. Weston. 



Fig. 3. 



Fig. 2. — Oyrtodonta? ungulata. a, right valve; 5, anterior extre- 

 mity. 



Genus Pterinea, Goldfuss. 



P. bellilineata, n. sp. — Left valve gently convex obliquely, semi- 

 elliptical ; hinge line long and straight ; anterior side obliquely rounded ; 

 uniformly curving into the ventral margin ; posterior side slightly concave, 

 below the cardinal angle, and then rounded into the ventral margin. 

 The beaks and anterior wing are not visible in the specimen, being 

 buried in the matrix. Surface with very distinct and slightly undulated 

 raised lamellose concentric lines, about two in one line. They cover 

 the whole surface up to the umbones. Obscure indications of radiating 

 stride can be made out. Length on the hinge line 15 lines ; height 12 

 lines. White Cliff; H. R. J. Richardson. 



