Rhabdosphaera, [110]

Rhabdospheres, [114]

Rhabdus, [183], [184]

Rhagon, [209], [213]

Rheotaxy, [20] f.;

its rôle in syngamy of Mammals and Sauropsida, [34]

Rhipidaster, [453], [463]

Rhipidodendron, [111], [112] f.

Rhizocrinidae, [588], [589], [590] f.

Rhizocrinus, [588], [591]