Local distribution of the gastropod mollusk Tritia trivittata. This species was recorded from 353 stations out of the total of 417 comprised within the limits of the map. It has thus the most general distribution of any species of animal dredged within these waters. The circle around the star, here and elsewhere among the mollusks, denotes the known occurrence of living specimens. Where the circle is wanting, either dead shells only were present or the point is not indicated in the records. The symbol has, however, been employed only in the case of shell-bearing animals
Nassa 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 scallop and its different habitat (Nassa usually being found on the tide flats) little damage is done.
