Historical reference: Do not rely on this information. It is very old. About this collection
Tellinacea, a group of Lamellibranchiata (q.v.), includes those forms with two adductor muscles (those by which the two valves of the shell are closed), a single pair of gills, long separate siphons, and a hrge foot. Tellina - the type genus - is common on our shores, and ranges in time from the Cretaceous period onward.