gems, pearl, Ceylon, Sri Lanka, Gulf of Manaar, pearl oysters, pearl formation

Jameson examines the identity, classification, and geographical distribution of the pearl and mother-of-pearl oysters, revising the subgenus Margaritifera and attempting to clarify confusion surrounding the names and relationships of its constituent forms. Drawing on museum specimens and earlier zoological literature, he discusses diagnostic shell characters, synonymy, and the geographic ranges of the various species and varieties, including important pearl-producing forms from the Indo-Pacific region. The paper is of particular relevance to pearl studies for its early systematic treatment of the mollusks responsible for natural pearls and commercial mother-of-pearl.