Enemies of the American Oyster 149 



and is killed quickly when immersed in fresh water. It 

 is not abundant in sea-water that is only slightly fresh- 

 ened. On the other hand, the oyster is naturally a 

 brackish water form. The natural ranges of the two 

 forms, then, are not the same, but overlap. It thus hap- 

 pens that almost the whole of Chesapeake Bay and the 

 shore of the Gulf of Mexico, while salt enough for 

 oysters, are too fresh for starfish, and in these regions 

 this curse of the northern industry is practically un- 

 known. 



It was not until about 1882 that it was recognized as 

 a serious menace to the northern industry. The reason 

 for this was not the sudden appearance of the form at 

 that time, but simply that the industry had previously 

 been confined to comparatively fresh waters near the 

 mouths of rivers, or streams, where the creature found 

 difficulty in perpetuating itself. It is usually on the 

 outer beds only that oystermen have great trouble with 

 the pest. 



The starfish or " five-finger " certainly does not reveal 

 its real character by its appearance, for among the shore 

 animals, few are seemingly more harmless. Its body 

 is made up of a central circular disk, a little more than an 

 inch in diameter in the species inhabiting Long Island 

 Sound and neighboring waters. From this there radiate 

 symmetrically five arms or rays, each five or six inches 

 long in a large specimen. The wall of the entire body 

 is composed chiefly of short rod-like plates of lime joined 

 together at their ends by muscles, and in such a way as 

 to form a network. Borne on these plates of the skele- 

 ton, and projecting outward over the entire surface, are 

 a great many short, blunt, spines. 



The mouth is situated on the under surface in the 



