?Archinacella arca aff. Wahlman, 1992, p. 83, pl. 3, fig. 7-10.
Description: : Shell is medium sized, nearly circular in outline, quite high and strongly convex dorsally and posteriorly. The lateral slopes are nearly flat and the anterior slope is broadly concave. Apex is distinct, bluntly pointed, slightly curved anteriorly, situated high over, and slightly past, anterior apertural margin, which is slightly convex. The posterior apertural margin is broadly convex and the lateral apertural margin is strongly arched, increasingly so posteriorly. Growth lines are fairly widely spaced in immature shell and in mature shell become more closely spaced and slightly irregular, showing middle wrinkling near base of anterior slope.
Ecology: Deposit feeder
Archinacelliopsis patelliformis Hall, 1842
Description: Shell is cap shaped, height is variable, and it is generally widest anteriorly. The apex is located distinctly anteriorly. Muscle scars (impression on the interior of the shell showing where muscles were once attached) are fused incompletely into a horseshoe-shaped scar that is open posteriorly. There are discrete accessory muscle scars in opening of horseshoe-shaped scar.
Ecology: Deposit feeder
