|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Bivalvia - Arcida - Arcidae
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|C. E. Weaver and K. Palmer 1922||Shell large and rectangular in outline ; nearly equilateral ; beaks
prominent, umbonal area broad ; hinge line straight ; cardinal area narrow ; dorsal
line sloping slightly from the beaks ; anterior end rounded, passing into the
ventral margin with a curve ; ventral margin only slightly curved, extending
abruptly into the posterior end ; posterior end straight ; posterior end is more
flaring and concave than the anterior end ; there is a tendency for a slight
umbonal ridge to extend from the beaks to the posterior ventral margin ; shell
ornamented with 22 flat-topped, wide, very prominent radiating ribs with interspaces
nearly equal to the width of the ribs.