Atrial cavity, [43], [44], [59], [63], [67]

Atriopore, [113], [115], [117]

Atrium, of Amphioxus, [113], [118], [121], [135]

Atypichthys, [666]

Atyposoma, [666]

Auchenaspis, [529]

Auchenipterus, [589];

A. nodosus, elastic-spring-apparatus, [358]

Auchenoglanis, [588]

Auditory organs, [387] f., [388];