107 
MARGARITA. 
Mytituus, Linnai, &c. 
Avicuta, Cuvier, De Lamarck. 
CHARACTER GENERICUS. 
Testa bivalvis, mequivalvis, alata, ad unum latus 
hians: al@ mequales: cardo adentatus: hgamen- 
tum internum in fosula subtriangulari repositum. 
ANIMAL byssoferum. 
PEARL-SHELL. 
GENERIC CHARACTER. 
Shell bivalve, unequal-valved, winged, with one side 
gaping: wings unequal: hznge toothless: ligament internal, 
placed in a somewhat triangular excavation. 
/ 
AniMat furnished with a byssus. 
This genus (called Concha Margaritifera, or Matrix 
Perlarum) produces the pearls of commerce*, respecting the 
formation of which, some of the most absurd notions have 
been advanced by ancient, and even by modern naturalists ; 
some conceiving them to be the eggs of the pearl shell; 
others, that they are produced by dew imbibed by the ani- 
mal in its supposed morning excursions to the surface of 
the ocean. 
Pearls seem to be the effects of a disease-} in the animal 
* An interesting account of the Ceylon pearl feshery, may be found in 
the Asiatic Researches, vol. 5. 
+ See the Memoirs of the French Academy for 1717, which contains a 
curious paper on this subject by Reaumur. 
