182 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 21, 



Left valve tumid ; the beak folding over ; covered witli regular, 

 elevated, concentric ridges. Right valve slightly tumid anteriorly, and 

 depressed near the posterior end ; covered with concentric, elevated 

 ridges which are less regular and less elevated than those on the left 

 valve ; sharply truncated at the anterior edge. 



Length 1^ inch ; breadth If inch ; thickness f inch. 



From subcretaceous hmestones between Sobral and Torres Vedras. 



I have named this species after Seiior Edwardo Augusto Boaventura, 

 to whom I am indebted for all the specimens from this locahty. 



Plate XXI. fig. 2 a. Right valve. 



Fig. 2 b. Left valve. 



Cyprina globosa, n. s. Pl. XV. fig. \ a k \ b. 



Subglobose; nearly smooth, with some irregular concentric wrinkles: 

 posterior side rounded, with two slight longitudinal depressions : um- 

 bones rounded and very thick ; lunette broad and ill-defined. 



Shell very thick. Anterior muscular impression very deep. 



Length 1| inches ; breadth 2 inches ; thickness 2 inches. 



Found in the upper beds of the hippurite hmestone at Lisbon. 



The specimen has lost the shell of one valve, and thus represents the 

 exterior of one valve and the cast of the interior of the other. It is 

 remarkable for the roundness and thickness of the valves near the 

 hinge and for the great solidity of the shell. 



Plate XV. fig. \ a k b. Two ^dews of the same specimen. 



Cyprina cordata, n. s. Pl. XV. fig. 2 a & 2 5. 



Ovate, thick, concentrically wi'inkled? Posterior side rounded. 

 Beaks incurved. Lunette large. Anterior extremity prominent. 



Shell thick, anterior muscular impression deep. 



Length 2\ inches ; breadth 2^ inches ; thickness 1| inch. 



From the upper beds of the hippurite limestone at Lisbon. 



The shell of this species seems to have been very liable to decay, as 

 while internal casts are very abundant, only one weathered specimen 

 has been found with the shell. 



Plate XV. fig. 2 « & 5. Two views of the same specimen, of 

 which the surface is much decayed. 



Cyprina securiformis, n. s. Pl. XXII. fig. 1-3. 



Cordato-triangular, with the dorsal margin continued in a regular 

 curve from the umbo to the posterior angle ; ventral margin rounded ; 

 anterior margin with a deep depression below the beaks, which are 

 placed very forward. The dorsal side is nearly pei'pendicular to the 

 rest of the valve and marked with two shght longitudinal carinse. 

 Surface nearly smooth, with some concentric wrinkles which are 

 stronger near the ventral margin. 



Length 2 inches ; breadth 2 J inches ; thickness 1 inch. 



Plate XXIL fig. 1. Left valve. 



Fig. 2. Dorsal view of another specimen. 



Fio-. 3. Hinge of a third specimen. 



