1901.] MOTHER-OF-PEAEL OYSTERS. 377 



the nacre. The anterioi* niargin, ventral to the hyssal deft, pro- 

 jects farther forward than in any other variety, so tliat a perpeii- 

 dicuhar lo the hing-e from its anterior end wonld cut off ahout -^ of 

 the valve. 



Colour greyish yellow or light brown, often resembHng that of 

 M. maxima. Eadial rows of spots very indistiiict and approximating 

 to ground-colour of shell. Inner surface of lip yellowish brown, 

 Nacre silvery \\'hite, with a narrow golden or brassy margin. 



Speciuiens from the Sandwich Islands and Mazatlan, and 

 occasional Panama examples, together with exceptional individuals 

 of 31. m. typica, link this form to Linnajus's species. 



Ilanley's name M. mazatlanica takes precedence of Eeeve's 

 IM. barbata for this variety. It has been referred to Avicula 

 fimbriata Dunker (1852) by Carpenter (1857) ; but the species 

 figured by Dunker (1872), pi. y. fi.gs. 2 & 6, as his Avicula 

 {Meleagrina) fimhriata, 1852, is certainly distinct from the 

 "Panama shell" of the trade, and probably represents a Central- 

 American form allied to M. vulgaris or M. siujillata. 



Geographical Distribution. Panama ; Gulf of California ; Mazat- 

 lan ; Vancouver. 



Specimens from the Sandwich Islands in the British Museum 

 are intermediate between this variet}^ and the type. 



It is interesting to note that the oceanic variety (cumingi) is 

 the darkest, the Australian and Malay shells are intermediate, and 

 the lightest colours are assumed by shells living on the shores of 

 the great Continents (vars. Zanzibar ensis, persica^ erythrceensis, 

 and mazatlanica). The most extreme of these, i. e. pej'sica and 

 mazatlanica, agree in having the posterior angle of the hinge 

 right or acute. 



Species 2. Margaeitifbba. maxima, n. sp. 



Type B.M. No. ] 901. 2.28.1; Basilaki (Moresby Island), 

 British New Guinea, pres. H, Lyster Jameson. 



Concha margaritifera (ex parte). Lister, 1685, fig. 222 ; 1696, 

 pi. 9 (prae-Linnean). 



Malacca i^earl oyster, Home, 1828, vol. vi. pi. 49. 



Meleagrina margaritifera (Linnaeus), Kent, 1893, chap. 5, 

 pi. xxxviii. 



The large white Mother-of-Pearl shell of Australian, Papuan, 

 and Malayan waters, " Silver-lip," " Gold-lip," &e. 



It is a singular fact that the largest and most valuable species 

 of Mother-of-Pearl Oyster has passed, hitherto, without a name ; 

 having been, no doubt, included by most writers under Linnseus's 

 species. 



Saville Kent, who was the first to point out clearly the dis- 

 tinctions between this shell and the " Black-lip," concluded that 

 the more valuable species was the type of Linnseus's description, 

 and recognized the Black-lip as Avicula cumingii Reeve. Pace 

 (1898) suggested that the Black-hp was the species originally 



