OF CONCHOLOGT. 57 



Scotland. To that gentleman the 

 British Conchologist is indebted for 

 the discovery of many new species. 



Genus 13th. — ARC A. Animal a 

 Tethys; shell bivalve, equivalve; hinge 

 with numerous sharp teeth, alternately 

 inserted between each other. Linn. 

 Si/st. 312. Plate 6th, fig. 13th. 



Linne divides this genus into two 

 families: *with the margin entire; 

 **with margin crenulated ; and has 

 subdivided each into two sections, 

 tbeaks recurved ; and |f beaks in- 

 flected. 



Habitation. Some of the Area are 

 affixed by the foot of the animal to 

 rocks ; and others lurk in the sand or 

 mud near the shore, generally be- 

 tween high and low water mark. 



The Area have only been found to 

 inhabit the ocean. 



This genus takes its name from the 

 strong resemblance the Area Noce, 

 and some others, have to the hull of a 



