2^it-slielh and Mussels 



6\ 



m- 



Right side of A)iomla^ with shell removed 



o, opening for hinge; m, adductor muscle ; 

 7t, calcified byssus 



attached to the upper valve and passes through tlie 

 lower one. It appears to represent the byssus-threads 

 of the Mussel and 

 Scallop united into 

 a solid mass. The 

 expanded end evi- 

 dently corrodes the 

 livincr surfaces to 

 which it attaches, 

 for it is frequently 

 found to be lodged 

 in a little pit. 



The animal varies 

 in colour from yel- 

 low to red and 

 brown. Its mouth 

 is large, and furnished with a pair of long slender 

 lips. As the animal does not burrow, and is usually 

 found solitary, it can develop its shell pretty equally 

 in all directions ; the mantle is therefore more or 

 less circular like the shell, its margin fringed with 

 two or three rows of yellowish filaments. Again, 

 because it is not a burrowing or otherwise 

 active animal, the white cylindrical foot is 

 very small. There is a variety {aculeatct) 

 in which prickly scales are developed on the 

 upper valve. 



The only other British species is the 

 Ribbed Saddle - oyster {A. ixttelliforinis), 

 smaller than the last, and attaining to little 

 more than half its dimensions. From 20 

 to 30 waved ribs radiate from the beak to the 

 margin, and the shell is often ornamented with 



Prickly variety 



of the 

 Sadd le-oyster 



