J40 SEA-SHORE LIFE 



Island and New Jersey. L. heros, Fig. 9S, ranges from Virginia to 

 I^nbrador, and N. diiplicata, Fig. 99, from Yucatan to Massachusetts 



Bay. They may be recognized by their 

 large size, light yellowish-brown or bluish- 

 Avhite color, blunt, rounded spire, and sim- 

 ple, round opening with a sharp-edged 

 lip. In L. heros the umbillicus, or cen- 

 tral cavity of the body whorl, is widely 

 open whereas in A^. duplicata it is practi- 

 cally closed by a plug. The whole shell 

 is also flatter than in L. heros. The ani- 

 i^z.e. pp.sorTHERNSANiJ- ji^qI jg gg large that when seen expanded 



COLLAR SNAIL. New Jersey. . i Ti • n i i • i i 



it seetns hardly conceivable that it could 

 withdraw into its shell. However, it can perform this feat very 

 rapidly, and then completely close the opening Avith its horny 

 operculum. 



The broad, muscular foot of these snails secretes a large 

 amount of mucous, enabling the creature to glide readily over the 

 bottom or bury itself beneath the surface, which it always does if 

 in danger of being stranded by the tide. The edges of the foot are 

 sharply angular, and a large piece forward of the head is reflected 

 back, making a thick, fleshy shield which serves as a ploughshare 

 when the animal burrows through the sand in search of prey. The 

 mantle is very contractible, and can be reflected uj^ward over the 

 shell so as to almost wholly enclose it. The surface of the shell is 

 thus bathed in the secretion from the mantle, and kept smooth as 

 is common with all mollusks ihat cover their shells in this manner. 

 A notch-like fold in the free edge of the mantle admits water into 

 the gill cavity. The head is provided with two sharp-pointed 

 tentacles. 



These creatures are carniverous and devour other mollusks, 

 including the young of their own species. They are especially 

 enemies of the clams. Applying the proboscis to the surface of the 

 clam shell, it bores through by means of its ribbon-like tongue, 

 which is armed with numerous rasping teeth. This boring process is 

 usually facilitated in carnivorous mollusks by a secretion of sul- 

 phuric acid. The hole bored is circular, and its sides beveled as 

 if countersunk, 



