SAXICAVA. 349 



valve, when adult, edentulous ; ligament external, more or 

 less promiuent. Muscular impressions strong, wide apart ; 

 pallial line interrupted, sinuated posteriorly. 



Syn. Chamsepholas, List. Glycimeris, Schum., not 

 Klein or Lam. Didonta, 8 chum. Rhombus, Eliomboides, 

 Blainv. Byssomya, Guv. Clotho, Faujas St. Fond. 

 Pholeobia, Biapholius, Leach. Hiatella, Baud. Arcinella, 

 Phil., not 8 chum. 



Ex. S. rugosa, Linnceus, pi. 94, fig. 1. Shell, S. rugosa, 

 fig. 1, a, 1, b. 



The Saxicava are few in species, and are usually found 

 burrowing in limestone rocks, the animal being fixed by the 

 byssus to the side of the crypt it excavates. They are also 

 found dwelling in holes of old oyster or other shells, and 

 among masses ofSerpula in the littoral and laminarian zones. 

 Sometimes they do considerable damage to sea-walls. They 

 inhabit the Arctic Seas, the Cape, the Mediterranean, and 

 the Canary Islands, ranging from low-water to 140 fathoms. 

 In the young state, Saxicava rugosa gapes at the superior 

 margin, and the hinge is composed of a small tooth in the 

 right valve, and two rather larger oblique teeth in the left 

 valve ; in this condition it is the Hiatella of Daudin, and 

 the Arcinella carinata of Philippi. 



Species of Saxicava. 



arctica, Linn. purpurascens, Souk 



australis, Blainv. rugosa, Linn. 



Cordieri, Desk. tenuis, Sow. 

 Guerinii, Payr. 



VOL. II. Z Z 



