Archicoel, [450]

Arcuothrix, [52];

transition between pseudopodium and flagellum in, [47] n.

Arenaceous Foraminifera, [58] f.;

Carpenter on, [63] f.;

labyrinthine structure in, [66]

Argas persica, [121]

Aristocystis, [599], [599]

Aristotle, [166]

Aristotle's lantern, of Echinus esculentus, [515], [516], [524], [525];