Enemies of the American Oyster 157 



The shell of the oyster drill, represented in Figure 40, 

 has a length of an inch or somewhat more. When the 

 fleshy parts of the body are extended one may observe 

 the flat muscular " foot," and projecting forward above 

 it, a proboscis-like extension of the head, on the end of 

 which is the mouth. Just within the mouth 

 opening, in a position corresponding to that 

 of the tongue of higher animals, is developed 

 a band of minute, hard, sharp teeth, which 

 together constitute what is known as the 

 lingual ribbon. 



When at work on the shell of an oyster 

 or clam, the foot may be seen to adhere 

 firmly to it, while the mouth is everted suf- FlG - 40.— The 

 ficiently to expose the ribbon. This is (Urosalpinx 

 pressed against the shell, and a slow, rotary cinirea). 

 movement is begun that finally results in the Drawn from 

 drilling of a clean, smooth hole directly 

 through it. Some of the results of this work are shown 

 in Figure 64. It is now only necessary for the drill to 

 remove the soft parts of the victim's body by means of 

 the proboscis or manubrium, which is thrust through the 

 aperture. 



The drill, or Urosalpinx, is most destructive to young 

 oysters. It seems to be unable to bore through the shell 

 of large individuals. While not nearly so destructive as 

 the starfish, it does much damage, because it is continu- 

 ally at work, and is so small that it falls through the 

 mesh of ordinary oyster dredges. In order to prevent 

 this, dredges are sometimes covered with fine-meshed 

 nets. 



Like starfish, oyster drills were formerly not numer- 

 ous on the New England oyster beds, but in recent years 



