Ophioxylon (plant), [629]
Ophisaurus, [538];
O. apus, [538];
O. gracilis, [538]
Ophthalmosaurus, limbs, [481], [481], [484]
Opisthocoelous, definition, [12]
Opisthoglossa, [140]
Opisthoglypha, [592], [606] f., [623] f.
Oppel, on classification, [7]
Oreobatrachus, [241]