﻿SAXICAVA.— Plate I. 



Hob. British Islands. — France. 



More smoothly rounded and less sharply angular 

 than Saxicava arctica, with more convex ventral and 

 dorsal margins. 



Species 4. (Mus. Brit.) 

 Saxic.wa sulcata. Sax. testd crassd, subcuneatd, 

 concentrice undis magnis profundiusculis rugatd ; 

 latere antico anrjusto, producto, subacuminato ; 

 umbonibus elevatis, margine ventrali profundi 

 excavato ; latere imstico lata, rotundatim angidato, 

 margine ventrali convexo, margine dorsali dcpresso, 

 margine terminali truncato. 

 The grooved Sa.\icava. Shell thick, rather cuneate, 

 concentrically wrinkled in large waves ; anterior 

 side narrow, produced, rather acuminated ; 

 umboes elevated, ventral margin deeply 

 excavated ; posterior side broad, roundly 

 angular ; ventral margin convex ; dorsal margin 

 depressed ; terminal margin truncated. 



Deshates ? MS. Mus. Brit. 



Hab. Clyde. 



The writer is uncertain respecting the authority for 

 this species, which certainly seems distinct from any 

 known forms of S. arctica^ or S. rugosa. It is repre- 

 sented in the British Museum by an odd valve from 

 the Clyde. 



Species 5. (Mus. Brit.) 

 Saxicava Pholadi.s. Sax. testd clongatd, suhmililiformi, 

 concentrice valide rugatd ; latere antico brevissimo, 

 angustiiiscvlo ; latere postico magis expanse, elon- 

 gate, oblique anc/ulato, margine dorsali recto ; mar- 

 gine terminali late truncato ; margine ventrali 



The Pholas-like Saxicava. Shell elongated, rather 

 mytilus-shaped, concentrically strongly wrinkled, 

 anterior side very short, rather narrow ; posterior 



side more expanded, elongated, obliquely angular; 



dorsal margin straight ; terminal margin broadly 



truncated ; ventral margin convex. 

 Lamarck. Anim. s. Vertebres. 

 Hab. Greenland. 



It is quite an open question whether this may not be 

 one of the numerous forms of Saxicava rugosa. 



Species 6. (Mus. Brit.) 



Saxicava solida. Sax. testd crassd, rhomhoided, 

 incequivalvi ; valvd dextrd projundd, ad umbonem 

 rnulto valvam sinistram altitiidine sujjey-anti ; latere 

 antico brevissimo, declivi, umbonibus fere termina- 

 libus ; latere postico hiangulato, angulis obliquis, 

 moniliformibus, margine terminali perpendiculariter 

 truncato. 



The solid Saxicava. Shell tliick, rhomboidal, 

 ina?quivalve ; right valve deep, much higher tlian 

 left at the umbo ; anterior side very short, sloped, 

 umboes nearly terminal ; posterior side biangular, 

 angles oblique, moniliform ; terminal margin 

 perpendicularly truncated. 



SowERBT. Proc. Zool. Soc, 1834. 



Hab. ? 



A very solid shell with two posterior keeled and 



partly beaded angles. 



Species 7. (Mus. Brit.) 



Saxicava flaccida. Sax. testd parvd, subovatd, tenuiiis- 

 culd, terminis rotundis, umbonibus magnis, fere 

 tenninalibus ; margine ventrali medio subexcavato. 



The flaccid Saxicava. Shell small, rather oval, 

 rather thin ; ends rounded, umboes large, nearly 

 terminal ; ventral margin a little excavated in the 

 middle. 



Gould. United States Exploring E.xpedition ? 



Hab. North America. 



