980 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [38] 
‘¢ Many persons mention the Nassa reticulata as a dangerous variety of 
periwinkle, quite as harmful as the preceding. My own observations 
and researches do not lead me to share this opinion. 
‘¢T must also speak of the Thére, a fish belonging to the family of Rays, 
and another formidable enemy of the oyster, which it devours after. 
having crushed it in its powerful jaws. When this fish enters a park a 
veritable devastation follows. The havoe they produce must be seen to 
be appreciated. During my first year here, I had to suffer from their 
depredations ; but [immediately putin practice the means which I had so 
fortunately employed at Arcachon, and which consists in increasing the 
number of pickets in such a manner as to hinder their advance. They 
always move in an oblique direction, when they sink to the bottom. Can 
my getting rid of them be ascribed to this contrivance? It is possible 
that, injuring themselves against the pickets a first time, they are not 
willing to run the risk again; or do these obstacles inspire them with 
fear? Weare tempted to believe so, when we consider the pusillanimity 
of the There. 
‘“‘ Hinally, more as a matter of curiosity than otherwise, I am going to 
mention a singular enemy of the young oyster, and this is the shrimp. 
But, as this animal requires a certain amount of space for its movements, 
it is difficult for it to commit great depredations about the collectors; it 
does some damage, however, in the following manner: 
‘‘ Tn order to break off the young oyster, the shrimp proceeds after the 
manner of a battering-ram. It poises itself some distance off from the 
point to be struck, and then pounces down upon it with all the speed it 
can acquire, directing its spur, which is powerful compared with the rest 
of its body, upon the shell, which it thus penetrates. This attack is re- 
newed, until it only remains for the shrimp to settle down upon its victim 
and devour it.” 
The star-fish, which the English oystermen dread so much upon their 
oyster banks, is little to be feared along the coast of the department of 
Morbihan. However, at@he county fair of Vannes, Dr. Gressy exhibited 
a Star-fish holding, entangled in its arms an oyster, the edges of which 
seemed to have been worn away by the file-like surface upon the under 
side of the rays of the star-fish. It is probable that, whether upon the 
banks or in the parks, the star-fishes feed upon oysters by seizing and 
holding them tightly, and filing away the edges, until the mollusk is 
sufficiently uncovered to be devoured by suction. 
Besides these enemies, which may be said to act directly, there are 
others which cause ravages none the less sensible, because produced in- 
directly. Thus the sea worm excavates cavities into which the oysters 
sink, become swallowed up in the mud, and die. The only preventive 
against them is to macadamize the muddy or clayey soil with gravel or 
broken shells. 
In speaking of the different zones of the parks, we have had occasion 
to mention the polyps, which attach themselves to the collectors, like 
