One of the two varieties of clam, the other being soft-shell clam. On the East Coast, hard-shell clams, also called by their Indian name, quahog, come in three sizes. The smallest are littleneck clams, which have a shell diameter less than 2 inches. Next comes the medium-size cherrystone clam, about 2½ inches across. The largest of this trio is the chowder clam, (also simply called large clam,) with a shell diameter of at least 3 inches. Among the West Coast hard-shell varieties are the Pacific littleneck clam, the butter clams from the Puget Sound. See also clam.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.