THE SHELL-FISH OF THE COAST. 27 



Natica (PI. 1, Figs. 1, 4), one of whose best rcprO' 

 sentativee is the common globular shell, of about 

 the size of an apple, which is found almost every- 

 where along the beach. The natics, with strong 

 carnivore propensities, are markedly predaceous in 

 their habits, moving about rapidly in their sandy 

 homes in quest of food, which they usually find in 

 the shell-fish buried at some little depth beneath 

 the surface. The making of the larger round holes 

 which appear in such perfection on the shells of 

 many of the bivalves is commonly attributed to the 

 Natica, but the exact amount of guilt attaching to 

 this creature has never yet been determined. The 



Natica extended. 



Naticas have certain peculiarities of structure which 

 it will be well to notice. You will observe, if you 

 have succeeded in finding more than the empty 

 shell, that the animal is completely retractile, and, 

 further, that it has cased itself in by means of a 

 horny lid or ' operculum,' which is attached to the 

 under surface of the creeping disk or foot. This 

 foot is greatly produced in front, where it is re- 

 flected back in the form of a hood, covering the 



