12 PEARLS [CH. 



pearls having some resemblance to the gems of that 

 name, or which have played some important part in 

 the scientific investigation of pearl formation. 



First and foremost mention must be made of the 

 Ceylon Pearl Oyster. The name oyster, however, is 

 here altogether a misnomer. The pearl oyster is 

 more closely related to our common edible mussel 

 than to our edible oyster. The Ceylon pearl oyster 

 {Margaritifera vulgm'is) is not very large, the adult 

 of about three and a half years of age measuring, on 

 an average, about 7 by 6 '5 centimetres. 



Margaritifera vulgaris occurs, in addition to the 

 Ceylouese waters, in the Persian Gulf, the Red Sea, 

 near the Maldive Islands (where however it does not 

 appear to be fished for pearls), East Africa, and the 

 Malay Peninsula. It is interesting to note that since 

 the opening of the Suez Canal this pearl oyster has 

 migrated into the Mediterranean from the Red Sea. 

 The pearls found in this species vary somewhat in 

 beauty according to the district in which the mollusc 

 occurs. 



Xext to the Ceylon pearl oyster, mention must 

 be made of other species of the same marine genus 

 Margaritifera which are fished for pearls, or for their 

 shells, if these are valuable enough for the mother-of- 

 pearl industry. 



The most valuable, and at the same time the 

 largest, mother-of-pearl oyster, is Margaritifera 



