ENLARGEMENT OF PARTS FRO 



remarks : " It seems extraordinary and beyond 

 that the Meleagrina should, of all the Conchifera, be the 

 one to resent the commensalism of the Pea-crab, which 

 has been known since the days of Cicero, Pliny, Oppian, 

 and Aristotle to inhabit the shell of the Pinna and the 

 Oyster, and has been recorded from Astarte, Pectunculus, 

 and at least some half-dozen other bivalves, with whom 

 it appears to live on the most friendly terms. It is the 

 females, however, which constantly reside within the 

 shells of the Conchifera, whilst the males are said to 

 avail themselves of favourable opportunities to visit the 

 females in their retirement." 



Whether or not the unlucky male in this case in- 

 truded himself upon Meleagrina at an unfavourable 

 period, and, finding no female Pinnotheres^ penetrated 

 so far beneath the mantle of the pearl-mussel as to be 

 unable to retreat, one thing is quite clear, namely, that 

 Meleagrina entombed the intruder in a cyst of pearl, 

 from which the clever pearl-button maker alone liberated 

 him. 



Increased thickness of the shell of an oyster from 

 irritation is comparable to the formation of thick skin 

 under similar conditions. The thin shells of " native 

 oysters " living in quiet shallow water stand in striking 

 contrast to the huge, rough, laminated shell of the 

 " North Sea oyster " which has to contend with the 

 pressure of a large volume of water and much buffeting 

 from a tumultuous ocean. So that a native oyster, when 

 compared with one from the North Sea, resembles the 

 hand of a courtier when contrasted with that of a 

 peasant. 



