Enemies of the American Oyster 161 



Mr. Ingersoll calls our attention to the fact that " Al- 

 drovandus and others of the naturalists of the Middle 

 Ages entertained a singular notion relative to the crab 

 and the oyster. They state that the crab, in order to 

 obtain the animal of the oyster, without danger to their 

 own claws, watch their opportunity when the shell is 

 open, to advance without noise, and cast a pebble between 

 their shells, to prevent their closing, and then extract the 

 animal in safety. ' What craft,' exclaims the credulous 

 author, ' in animals that are destitute of reason and 

 voice/ " 



Every one who eats oysters has observed the small 

 oyster crab that lives in the mantle chamber. Only the 

 female is found within the oyster's shell, and the male 

 has rarely been seen. This small creature is not an 

 enemy, but simply a guest. It has been suggested that 

 she consumes organic particles brought in by the water 

 currents; but it may be that the masses of mucous secre- 

 tion that collect in the mantle chamber constitute " the 

 chief of her diet." This, however, is proposed without 

 actual observation to support it. 



Members of the mussel family near allies of the 

 oyster while they do not prey on their cousins, often 

 smother or starve them. They frequently become fear- 

 ful pests to the oyster culturist, especially in southern 

 waters. Their young, finding a suitable lodging-place 

 on oyster shells, congregate on them in numbers, at- 

 taching by the many tough fibers spun by the byssus 

 gland. They may become so numerous as completely to 

 cover the oysters and prevent the opening of their shells, 

 which, of course, means death. Even if this does not 

 occur, they strain out of the water the same organisms 

 that the oysters must have for food, and the latter fail 



