148 



Shell Life 



of its genua, it is a sand-dweller, and its range 

 is from extreme low water to 4 or 5 fathoms. It 

 attains a maximum breadth of 2 J inches, and fairly 

 large specimens are used for food in the west of 

 Ireland. 



Of the Gapers {^[ya) we have only three species, 

 and one of these we have already figured as a type 

 of the sub-order. The siphons are connected 

 throughout their length, and though they may be, 

 and are at times, completely withdrawn into the 

 shell, they are usually kept fully extended. This 

 has caused the hinder end of the shell to gape 

 widely. They are deep burrowers, and therefore 



Hinge and carti 



process of Gapers 



assume the position shown in our figure, the foot 

 downwards and the siphons reaching straight up 

 throuixh sand or mud to the water above, with the 

 long axis of the shell at right angles with the 

 surface. Looked at from this point of view it will 

 be seen that the fore-end of the shell is shaped like 

 the bows of a boat, that the tongue-shaped foot 

 may pull it down more easily. These shells arc 

 commonly buried to a depth of eight inches, some- 

 times a foot. There is a remarkable development of 

 the hinofe-teeth beneath the beak of the left valve in 

 the shape of a hollow shelf to hold the cartilage, 

 with corresponding ridges to fit it in the right 

 valve. 



