OYSTER-CULTURE IN FRANCE. 
865 
II.— THE OYSTER IN FRANCE. 
ITS SPECIES AND CHARACTERISTICS. 
In the French markets oysters are first distinguished as either u fiat” or “Portu- 
guese” (Plate lx vm). The former is the oyster of Northern Europe, Ostrea edulis , 
esteemed for its flavor and commanding a higher price; it is the species that is espe- 
cially cultivated. The latter, 0. angulata, is a modern importation, lacking in flavor, 
introduced as a substitute for the more delicate edulis. 
The flat oyster , as the name implies, is readily recognized by the shape of the 
shell. This is round in outline, flattened, large in proportion to the size of the animal. 
The shells are often quite smooth outwardly ; the lower valve, spoon-like in our 
American species, is scarcely as concave as a shallow saucer. 
The Portuguese oyster is typically long and irregular. One valve is deeply trench- 
like and contains the entire animal. The opposing valve is smaller, thinner, and 
recurved. The shell is heavy, rough and angular without, and coarse of texture within. 
When the shell is opened, the oyster appears slaty or bluish in color, outlined with the 
broad, jet-black margin of its mantle. Its taste is salty, bland, peculiar to itself, and 
somewhat sweetish. The flat oyster shrinks vastly on its opened shell, is faint in color, 
with a brown or pinkish margin. It possesses that piquant taste, perhaps slightly 
metallic or “ coppery,” so highly prized by the connoisseur. The contrast between 
the species in point of taste is considered more striking than the outward differences 
in shell. 
As regards natural conditions of living, the flat oyster occurs rarely in clusters 
and is found in deeper and salter water (sp. gr. about 1.026*). It may, moreover, 
slightly change its position and thus tend to keep itself above the mud. The Portu- 
guese oyster occurs naturally along shore and in clusters, in water of a less density 
(about 1.023) and of a somewhat higher normal temperature. 
It may be of interest to continue the question of differences in order to understand 
more clearly the position occupied by our American oyster. 
The long-discussed bisexuality of the flat oyster is in Europe generally conceded ; 
the American and Portuguese species are regarded as monosexual. If the flat oyster 
possesses this anomalous sex character, its genealogical relationship to other species 
will be difficult indeed to determine. The Portuguese oyster, still looked upon popu 
larly as a Gryphcea , must take precedence from geological antiquity. It certainly is the 
least prone to form varieties. The American oyster appears to be intermediate. The 
flat oyster is in many ways most specialized, and presents over thirty recognized vari- 
eties, several of which were formerly regarded as distinct species. 
* The extreme saltness of the waters of the French grounds shows quite clearly why the introduc- 
tion of the American oyster has always heen unsuccessful. Our oyster is comparatively a brackish- 
water form, occurring naturally in river mouths and sounds liberally supplied with fresh water (sp. gr. 
1.017). At Arcachon, where the density of the water is low (1.022 to 1.024), American oysters have been 
known to live for years, but without reproducing. 
