affinity to Cuculi, [241];

O. cristatus, [241], [242]

Opisthodactylus, [45]

Opisthoprora euryptera, [437]

Ophrysia superciliosa, [218]

Orange colour in Birds, its nature, [3] n.

Orbit, [20]

Orchesticus, [575]

ὄρχιλος, [426]

Orchilus ecaudatus, [473]