1908. 



NATURAL SCIENCES OF PHILADELPHIA. 



and, thirdly, it may wedge its shell between the valves of the Venus. 

 By contracting its coliimellar muscle it may actually wedge the valves 

 apart. Venus is much more sensitive to mechanical stimuli than is 

 Ostrea. Venus never opens its valves of itseK when it is in the grasp 

 of a Fulgur, while Ostrea, after the first shock, opens wide its valves as 

 if no danger were near. 



Fulgur and Sycotypus often break their own shell when opening 

 oysters and clams, and this accounts no doubt for the irregular growth 

 lines seen on their shells. 



This method of inserting the margin of a gasteropod between the 

 valves, of a Lamellibranch has been noticed before. Francois (1890) 



Quahog shell clipped by Fulgur. 



briefly reports that Murex fortispinna has a special tooth on the margin 

 of its aperture for the purpose of inserting between the valves of Area, 

 It may be that this manner of attacking the soft parts of bivalves is a 

 very common habit of Prosobranch mollusks. 



All writers recognize Fulgur and Sycotypus as pests to the oyster men. 

 How many oysters will be destroyed will depend on the average num- 

 ber eaten in a given time. Although I have found them to eat two 

 oysters one day and two the next, there follows a long rest period 

 where the individual remains buried in the sand — sometimes for days, 

 sometimes for months. 



Notwithstanding that Ingersoll (1884) says, "It is needless to say 

 that they do not burrow at all,"- 1 find that they are buried about 65 



