Astroscleridae, [194]

Astylus, [287]

Atelecrinus, [588], [594]

Athoria (usually placed in a subfamily Athoriinae of the Physonectidae, [307]), [300]

Atolla, [322];

A. bairdi, [322];

A. gigantea, [322];

A. valdiviae, [322]

Atollidae, [322]

Atoll, [390] f.