290 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



attacked, as after they become about 2 inches long the shell is stout 

 enough to resist this foe. The loss sustained from this source is very 

 great, as the drills are often present in large numbers and continue 

 their work throughout the year. 



The two large conch-like gasteropods of the Atlantic coast, Sycoty- 

 pus canaliculatus and Fnlgur carica (plate xv, fig. 4), also feed upon the 

 oyster, from their size being capable of attacking the largest individ- 

 uals. These periwinkles, " winkles," or conchs, as they are variously 

 called, appear to do comparatively little damage, as they are not pres- 

 ent in sufQciently large numbers anywhere except perhaps on the coast 

 of Florida. 



Other gasteropods doubtless feed uj^on tlie oyster, but not to an 

 extent worthy of consideration. 



Upon brackish- water beds the starfish (plate xyi) is not usually 

 troublesome, and in Chesapeake Bay it is practically unknown, but in 

 Long Island Sound, and especially upon the offshore beds in the more 

 saline waters, it is the most destructive enemy with which oystermen 

 have to contend. It is there extremely abundant at times, but it is a 

 migratory form, and sometimes certain beds are unmolested while others 

 nearby are almost ruined by its inroads. The appearance of this pest 

 upon the beds is without warning, and frequently the ground is almost 

 devastated before the owner is aware of their presence. Vast swarms 

 or schools sweep across the beds, devouring the oysters in their path. 

 The migration is said to take place in the form of a "winrow," moving 

 in some cases at the rate of about 500 feet per day. Apparently the 

 only way to stop the march of these hordes is to catch them up by some 

 of the methods indicated in pp. 313-31(1. By energetic work the damage 

 may often be confined to the beds at the edge of a cultivated area. 



The starfish begins its destructive work soon after it abandons its 

 free-swimming larval condition, at a time when it is hardly larger than 

 a pin's head, and continues it through life. At first it feeds upon the 

 tiny spat, but as it grows it increases the size of its prey, though even 

 the full-grown stars rarely feed upon oysters over two, or, at most, 

 three years old. Small oysters are often taken bodily into the stomach 

 of the starfish, a proceeding which is of course impossible with large 

 ones or those firmly attached to large cultch. It is not definitely known 

 how the oysters are opened, but Dr. Paulus Schiemenz has pretty con- 

 clusively demonstrated the probability that they are actually pulled 

 open by muscular effort on the part of the starfish. 



If the coimmoin starfish be examined there will be found on the under 

 surface of each arm four rows of closely crowded suckers or feet extend- 

 ing from the mouth to the tips of the arms. These feet are tubular 

 and are extended by having a fluid pumped into their cavities by a 

 special apparatus in the body of the starfish. The suckers at the ends 

 may be caused to adhere to foreign bodies with great tenacity, and if 

 the hydrostatic pressure be then relieved and the muscles of the stalks 

 of the feet contract, a strong pull may be exerted by each foot, either 



