Handbook of Paleontology 153 



(S. lineata) ; another (S. groenlandica) is an arctic 

 species that extends south to New England. These 

 shells get their name from a peculiar scheme of decora- 

 tion that can not be mistaken when once noted. They 

 are usually pure white with rounded whorls. The 

 whorls are crossed at even distances by greatly ele- 

 vated, smooth ribs which give the basis for the popular 

 name. Scaphopods or Elephant's Tusk Shells are, 

 strictly speaking, not littoral, as they range into deep 

 water. Two species (Dentaliiwi dentale, Entails strio- 

 lata) are exceedingly common in the New England 

 coastal waters at very moderate depths and are some- 

 times cast upon the beach during storms. They are 

 one inch to an inch and a half long and are shaped 

 like elephants' tusks, slightly curved, white, round, 

 hollow tubes. They live buried in mud and feed on 

 infusorians and other microscopic organisms. 



Bivalves are as characteristic of sandy bottoms as the 

 snails. There are several clams that are common, some 

 of them already familiar. The Soft-Shell Clam {My a 

 arenaria), often called the "long clam" or "nanninose" 

 is the common soft-shell clam of New England and is 

 highly esteemed in the market. The shell is quite thin 

 and brittle. This mollusk is found between tides in 

 sandy, muddy, pebbly or even rocky ground if it can find 

 material into which it can burrow and hide, and it lives 

 in the burrows with the long, extensible siphon pointing 

 upward. It is common in sheltered banks of bays and 

 estuaries between tide limits. This clam ranges from 

 the Carolinas to the Arctic and also occurs on the north- 

 ern coasts of Europe. Along the Maine coast it is gath- 

 ered and sold for bait to the Banks fishermen. The 

 Round Clam {Venus mercenaria), also known as the 



