Zoological Illustrations Series II/Plate 55



It is the animal of this genus of Shells, which in sickness and disease, produces the true oriental Pearl: the costly ornament of sovereigns, and the chaste foil of beauty. An interesting account of the Pearl fishery of Ceylon, will be found in Mr. Wood's entertaining Zoography, extracted from Percival's History of that island.

The present is a small species, seldom exceeding the size of the figure: in young shells there is a cardinal tubercle in our valve, which disappears with age. The Pearl-oysters are nearly all inhabitants of warm seas; the species require much elucidation.

The genera, above enumerated, appear to present such a series of affinities, as to justify our suspicions that they form a natural group: the more so, as their analogies may be traced among the perlacious fluviatile shells, forming our family Unionidæ. If further investigation should confirm the correctness of this idea, the sub-genera will, of course, become types of form; bearing the same relation to the genera, as Dipsus does to Anodon, or Castalia to Hyria.