Shell orientation terminology among the Bivalvia (Mollusca): Problems and proposed solutions

Abstract

Traditional terms used to describe shell orientation in bivalves are unsatisfactory in three important ways: 1) for poorly known bivalve taxa, unbiased and directionally neutral terms are sometimes needed to replace anterior and posterior where data are incomplete; 2) there is a striking absence of simple terms to apply to the long and short ends of the shell; and 3) the term lateral is either incorrectly or inconsistently applied. in the following discussion, I shall explore each of these issues and suggest remediation.