EUROPEAN METHODS OP OYSTER-CULTURE. 
369 
account of tlieir crowded situation, fingerlike in shape, with a narrow, knifelike pro- 
jecting margin. A further advantage gained by clustering is doubtless that of better 
feeding conditions, not merely in being raised from the stilling seaweeds, but as less 
disturbed by bottom sediment stirred up by storms. 
There can be little doubt that the Tagus, if undisturbed, would produce raccoon 
reefs as remarkable in many regards as those of May Eiver, South Carolina. The 
comparison with raccoon oysters might even be continued farther than in the irregular 
shape of shell, in its often thin, watery, and tasteless character caused by its exposed 
position. The color of the flesh, however, is not that of the southern oyster; it is an 
opaque blue white, often dark slaty, the fringing edge of the mantle, as already noted, 
being broad and jet black, the sense papillae long and coarse. 
It seems extremely significant that these two oysters, the Portuguese* and the 
Virginian in its raccoon variety, become remarkably similar when' their physical 
conditions are paralleled. It is likewise noteworthy that the same natural method of 
culture, transplanting seed from shallow into deeper water, becomes also paralleled. 
There is apparently less difference between the typical raccoon and the northern 
oyster of the American coast than between the raccoon and the angulata of Portugal. 
The taste, the peculiar slaty tint, and broad sensory mantle rim of the Portuguese 
oyster are not discriminative. These characters appear to become acquired by the 
American species when introduced into European waters. The original quality of 
the American oyster appears to deteriorate steadily from the time of its introduction? 
and this species thus often attains a well-earned reputation for inferiority. The greater 
saltness of the European localities has been noted as one of the conditions that have 
rendered unsuccessful the introduction of the American oyster, and it certainly has an 
effect in checking the spawning habits, for in no instance has a well- authenticated 
successful spawning been noted in England, France, or the Netherlands. Where the 
American oyster has been introduced it has invariably lived, but has not succeeded in 
regaining its original quality. Where the density has been as low as 1.023 to 1.024, it 
has gained in flesh, but has become (e. g ., Arcachon, Jerseke, and Whitstable) of the 
opaque, clayey, Portuguese type, rivaling the Portuguese oyster in its peculiar taste. 
The angulata , moreover, like the raccoon, when given the better conditions of 
deeper water feeding, and when transplanted in cultural processes, as at Arcachon, 
develops, as might naturally be expected, a long, regular, and well-shaped shell, 
almost losing its marginal, involuted angularity. The raccoon oyster becomes by 
cultivation creamy white, with a flavor not unlike the Whitstable native , but the 
angulata assumes its slaty color and coarseness in texture and taste that have very 
naturally rendered it of inferior commercial value. On this account it is not the 
most thankful task to compare the Portuguese to the American oyster — to suggest, in 
fact, that it is but a variety of the Virginian species. But it is not improbable, every- 
thing considered, that the angulata (derived perhaps at no remote age from the 
more generalized variety-forming American .species), has been produced through the 
local agencies of feeding conditions and increased water density. It reverts most 
clearly to the American species through the raccoon variety, its plicated shell rim 
being not more than a variation of that of the less plicated raccoon. Shell plication, 
which has been made of such value in specific discrimination, can hardly be given 
great weight after its variation in this regard has been examined under natural cou- 
*Cf. Winslow, as to similarity in sex character and development, Rep. Com. of Fish. Md., 1881, 
p. 68; for edulis should he read angulata. 
F.C.B. 1891 24 
