24 



filed through. The Purpura is provided with a long narrow pro- 

 boscis over the end of which works back and forth a ribbon 

 lined on the outside with sharp recurved rasps. The ribbon or 

 radula, as it is called, is formed just as fast as the teeth are 

 worn down. The result is that when examined under the 

 microscope the end rasps are found to be nearly flat; and they 

 gradually appear sharper as they near the base. By a steady 

 long-continued to and fro movement of the ribbon over the 

 end of the proboscis, the shell of the oyster is gradually bored 

 or filed through. 



After the oyster has been partially digested and killed, it 

 opens its shell the least bit, and the currents carry down w^ith 

 them the scent of the dying oyster. This is readily detected by 

 other drills, and they start up against the current to find and 

 share in the bountiful. feast prepared by one of their fellows. 

 The conch will notice the scent as much as eight or ten feet 

 down stream and will work its way up, travelling always to- 

 wards the source of the scent, i. e. directly against the current, 

 whereas one six inches away from the oyster on the upside, will 

 show no sign as having noticed the odor; showing that these 

 animals detect their food by smell, and that this scent is very 

 acute. Thus it is that a single oyster is often covered with 

 several Purpura and there are others waiting around, working 

 to get their "foot" into it. 



The drill like its cousin, the Lunatia, is seldom if ever found 

 in localities where oyster raising is the most profitable. They are 

 not found in the brackish wat^r of our inland lakes. In fact, 

 they are seldom seen in water under 1.0150 density. They are, 

 however, a source of annoyance on all of the transplanting 

 grounds. There is no practical method of getting rid of these. 

 There numbers may, however, be diminished by working over the 

 beds and separating the drill into a recepticle and throwing them 

 on dry land in summer and removing them to fresh water in 

 winter. In summer, the heat of the sun is sufficient to kill them, 

 before they can find their way back to the water, even if only 

 a few feet distant. 



The Drum-Fish.— This dreaded pest of our waters is found 

 in the salt water everywhere on the coast, and often wanders up 

 into the brackish streams, either unintentionally, or in search of 



