rays, and other aggressive dle.1111e., while it Wage. a passive fight against starvation and suft(wa tion with mussels, baroacle=, sponges, worms, aquatic vegetation. and other or luxuri ant organisers growing on the beds.
oceur= from the Cull of Saint Lawrence to t he tropics, but bet ween Ca pc ilreton and Cape Cod the Sheep=cot ]liver. Maine. is its only locality. It has also been introduced in San Francisco Bay, where it breeds to a limited ex tent. The yield of Eastern oysters at the begin ning of the present century Via, as follows: The greatest production is in Chesapeake Bay, where the principal yield is from the natural beds. Most of the oysters from New England and from New York and the outer eoast of New Jer sey are produced by planted beds: the entire yield of the Pacific Coast is similarly derived, and there has been recently a considerable increase in oyster culture in New Jersey, Virginia. and other States. The number of persons engaged in the industry is estimated at upward of 60,000, but as many of them are employed part of the year in other fisheries, farming, etc., definite sta tistics are not available. Baltimore is the most extensive market and New York has a consider able export trade with Europe.
The native oyster of the Pacific Coast is I istrca urida, a small thin-shelled species. It is her maphroditic, and. like the European oyster, re tains its young for a time in the mantle cavity. In 1901 159.340 bushels, valued at $251,192, were marketed. principally on the Pacific Coast.
The European oyster f().virea tiuii.cl is found from Italy to Norway. It is a round thin-shelled species, more shapely than the American species, and hermaphrthlitic. first female and afterwards male. it is less prolitie than its American rela tive and the young undergo considerable develop ment in the mantle chamber of the mother. It thrives in water of full. or almost full. organic density. The Portuguese oyster 1001'ra uronlntn1 'sexually and in its habits more closely re sembles (Islam irginieu.
The oysters of Japan are ORtrea eueullata, which occurs in shallow and moderately brackish or moderately salt water throughout the whole archipelago: and Ostrea gigas, a very large salt water species found in deep water. Many other
p .s ecie of Ostrea are found in temperate and s tropical seas throughout the world.
Foss'', OYSTERS. The oyster family appears to have had its origin in some imperfectly known forms, such as Ostrea nofiili.s.sima of the Car boniferous. The family is found also in the Permian. In the Triassic it is represented by a strongly idicated form. Alectryonia, which form becomes more prominent in the Jurassic and Cre taceous, There are also the common arcuate shells of Grypluea and Exogyra in the Jurassic and Cretaceous. Ostrea itself is known in the Mesozoic, but it attained its maximum of size and abundance in the Tertiary. The sandy marls 14 this period in the Southeastern United States often contain great numbers of very large speei mens of oysters, especially of two species, Ostrca t;corwjarra and Ostrra selheformis. Consult White, C. A., "A Review of the Fossil Ostreithe of North America and a Comparison of the Fos sil with the Living Forms," Annual Report of the ('mitred States Geological Surrey, vol. iv. (Wash ington, 1883).
OvsrEn CuuruaE. Owing to the exhaustion of the natural beds and their inability to supply the demand for oysters, it has been found neces sary to resort to artificial methods of production, effecting (1) an increase in the number of eggs fertilized ; (2) an increase in the surfaces avail able for fixation, and also of the number of spat attaching; (3) the saving of spat and young oysters which would naturally fall victims to (monies and adverse physical conditions; and (4) the utilization of barren bottoms and natu rally unavailable food supplies. But a small part of the area under water suitable for oysters has been utiliz«1 by nature, mainly for lack of suitable bodies for the attachment of the young. In the United States such barren bottom is util ized by clearing it of all rubbish and either plant ing 'cultele to collect the spat, or else young oysters (seed), that they may improve in size, shape, and quality under conditions safer and more favorable than in their original environ ment. In certain places either method may suc ceed. but commonly a locality is better adapted to one than the other.