Fig. 94. .\nssa obsoleta (the little black winkle of the tide flats) devouring 

 a scallop. These little scavengers swarm over the scallop. Occasionally one is 

 active enough to get between the valves, forming a wedge which permits the entrance 

 of others, which quickly consume the scallop. Owing to the alertness of the scal- 

 lop and its different habitat (Nassa usually being found on the tide flats) little 

 damage is done. 



