Rosemarie Mulholland 1984 <p>Two species of hard clams occur along the Atlantic and Gulf of Mexico coasts of North America: the southern hard clam, Mercenaria campechiensis Gmelin 1791, and the northern hard clam, ~lercenaria mercenaria Linne 1758 (Wells 1957b). The latter species, also commonly kno\'m as the quahog, was formerly named Venus mercenaria. The two species are closely related, produce viable hybrids (Menzel and Menzel 1965), and may be a single species.</p> application/pdf en U.S. Fish and Wildlife Service Habitat Suitability Index Models: Hard clam reports