1901.] MOTHER-Or-PEARL OYSTERS. 385 



Avicula (Meleagrinci) badia, Danker, 1852, p. 79 ; 1872, p. 12, 

 tab. 2. fig. 7 ; no loc. 



Savigny, 1811, pi. 11. figs. 8 & 9. 



As Schumacher's figure, and the one by Chemnitz to which he 

 refers, are evidently typical Eastern Lingah shells (from convexity, 

 posterior " auricle " of hinge-line, sharp separation of the inner 

 surface or the rostrum from the general surface of the nacre by a 

 Avell-detined ridge, and distinct anterior and lateral teeth in 

 Schumacher's figure), the name vulgaris must replace the more 

 iamWmv fucat a (Gould) for this species. 



This shell is extremely variable, and young examples have been 

 described as distinct species over and over again, while, until 

 comparatively recently, the grown shell has been confused by many 

 writers with M. margaritifera. 



It is highly probable that some of the described forms which I 

 am still treating as separate species will, on better acquaintance, 

 prove to be merely geographical races of M. vulgaris Schumacher. 



Geograjpliical Distribution and Variation : — 



Ceylon and Southern India. The Ceylon Pearl-Oyster is the best 

 known local form of this species. It frequents the Gulf of 

 Manaar, Palk Straits, and the Southern coasts of India. It differs 

 from most other local races in its lighter colour, and the whitish 

 or pink ground-colour of the interior of the lip. 



Maldive Islands. Mr. J. Stanley Gardiner, on his recent visit to 

 the Maldives, found this species fairly plentiful there, but not in 

 extensive beds. Unlike M. margaritifera, this shell is not fished 

 by the natives of the Maldives. 



Mr. Gardiner's specimens closely resembled those from Ceylon, 

 and were at once referred by Captain Donnan to the same 

 species. 



. Persian Gulf. The Lingah shell of the Persian Gulf belongs to 

 this species. It is distinguishable from the Ceylon form by its 

 darker colour, the exterior being usually more purple and the 

 radial markings almost black. The interior of the lip is dark red. 

 The shell attains somewhat larger dimensions than in Ceylon waters. 

 It is shipped in quantities to the London markets, but is of small 

 and fluctuating value, ovving to large supply and limited demand. 



Bed, Sea. Throughout the Ked Sea this shell is common, but is 

 fished almost exclusively for pearls. There are a number of 

 specimens from the Red Sea in the British Museum, but with one 

 exception (Aden, Major Yerbury) they are very young. The 

 Aden specimen is very like a Ceylon shell. 



\_Mediterranean. Since the opening of the Suez Canal this species 

 has wandered into the Mediterranean. There are typical examples 

 from Alexandria (W. B. Tegetmeier) and Mnlta (Col. Peildeu) in 

 the British Museum. An account of this interesting immigration 

 has been published by Vassel, 1896.] 



East Africa. Specimens from Mauritius (B.M. ; Mus. Cuming), 

 S. Africa (B.M. ; J. H. Ponsonby Coll.), Bazaruto Isl. (do.), and 



