Fenton and Fenton 1937 describe pelecypod burrows and trails near Dawson Pass.    From Wordnik.com.  [Glacier National Park Geology & Paleontology: Part 4 - Siyeh] Reference

It may thus be told from the pelecypod mollusk, such as the clam, whose two valves are not far from equal in size, each being divided into unequal parts by a line dropped from the beak.    From Wordnik.com.  [The Elements of Geology] Reference

Molluscs, 420; eyeless, 309; gasteropod, 348; pelecypod, 417; lamellibranch, 418.    From Wordnik.com.  [Lamarck, the Founder of Evolution His Life and Work] Reference