|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||Age range and collections|
Rhynchonellata - Atrypida - Atrypidae
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.
|A. J. Boucot et al. 1964||Subequally biconvex, subcircular,
transverse, or elongate shells commonly
without a well developed fold and sulcus.
Brachial valve may bear a shallow furrow posteriorly.
Ornament as in Atrypa. Dental lamellae present or obsolescent. Pedicle valve muscle field non-flabellate. Striated area for diductor attachment lacking in the brachial valve.Sockets not crenulated. A stout myophragm may be present. Brachidium as in Atrypa. A specimen of Atrypa reticularis is illustrated for comparison (pl. 126, figs. 1-5).