Class VI. ARCA. ARK-SHELL. 



215 



GENUS XIII. ARCA. AUK-SHELL. 



Animal, a Tethys. 

 Shell equivalve. 



Teeth of the hinge numerous, inserted between 

 each other. 



* With the edge entire ; beaks inflected. 



Lin. Syst. 1140. No. \6g. 



Gm. Lin. 3306. 

 Borlase's Nat. Hist. Cornw. 



tab. xxviii. jig. 15, 16. 

 List. Conch, tab. 368. 



Mytilus. Matthiol. apud Dios- 



cor. lib. ii. c. 5. p. 301. 

 Lin. Tr. viii. 91. 

 Mont. Test. Br. 13g. t. 4./. 3. 

 A. tortuosa. Br. Zool. iv. 97. 



A. with a rhomboid shell, deeply striated from 

 the apex to the edges ; breadth half an inch. 



Inhabits Cornwall; found also near Wey- 

 mouth ; extremely rare. 



1. NOiE. 



distorted. 



Mont. Test. Br. Sup. 51. 



* A. with a finely reticulated shell, of an uni- 

 form purplish brown color, destitute of any 

 colored bands ; length three quarters of an 

 inch, breadth an inch and a half. 



Found in Devonshire,, Cornwall, and Scot- 

 land. 



2. FUSCA. 



