LUNATIA. 



339 



yellow ; umbilicus large, rounded, displaying the whorls nearly to 

 the summit, coarsely wrinkled, the callus covering only a very small 

 segment of it. Operculum horny. Ordinary length, two and a half 

 inches ; breadth, two inches. 



It is found on sandy or muddy beaches along the whole coast ; 

 but much more seldom to the south than to the north of Cape Cod. 

 Eastport ( Cooper^ ; Nova Scotia ( Willis^ ; Gaspe (^Bell) ; Gull 

 Island (^ Smith). 



This shell is distinguished from all others by its inflated, globu- 

 lar appearance, and its simple, deep umbilicus. It very much re- 

 sembles an Ampullaria, and is most probably the Natica ampuUaria 

 of Lamarck. It also grows to a larger size than any other known 

 species. I have one specimen the greatest length of which is four 

 and a half inches, and greatest breadth three and a half inches ; 

 and I have seen one five inches by three and three fourths inches. 

 The shell is light for its size, and its whole structure and appear- 

 ance are very simple. 



This, in common with other species of Naticid(E^ is very voracious, 

 and plays a conspicuous part in devouring the dead fish and other 

 animals which are thrown up by the tide. Many of the shells 

 thrown upon the shore are found to be perforated with a small 

 round hole. This is done principally by the different species of 

 Lunatia. They have the power of perforating shells, it is generally 

 supposed, by discharg- 

 ing an acid which de- 

 composes the shell ; and 

 through the aperture 

 they extract the juices, 

 and destroy the lives of 

 the otherwise secure in- 

 habitants. Their foot is 

 very large, so as com- 

 pletely to envelop the ob- 

 jects on which they prey. In moving, they liurrow in the sand, so 

 as to be almost entirely concealed by it, and their place is gen- 

 erally indicated by a small heap of sand. 



The singular nidus, in which the animal of Lunatia deposits its 

 eggs, has been an object of much curiosity and speculation. It is a 

 mass of sand glued together into the shape of a broad bowl, open at 

 the bottom, and l)roken at one side. Its thickness is about that of 

 an orange-peel, easily bent without breaking when damp, and when 



609. 



Animal of L. heros. 



