ii. 345

_Opisthodelphys_, ii. 418

_Opisthostoma_, ii. 520

_Opisthoporus_, ii. 520

_Oporornis_, ii. 279

_Opossum_, extinct in European Miocene, i. 121

Opossums, ii. 248

_Opsariichthys_, ii. 452

_Opsiphanes_, ii. 472

Orang-utan, ii. 171

_Orca_, ii. 209

_Orcaella_, ii. 209

_Orchesticus_, ii. 99

_Orchilus_, ii. 101

_Oreas_, ii. 223

_Oreicola_, ii. 260

_Oreinus_, ii. 452

_Oreocephalus_, ii. 401

_Oreocincla_, ii. 256

_Oreodeira_, ii. 401

_Oreodon_, N. American Tertiary, i. 138

_Oreodontidæ_, N. American Tertiary, i. 138

_Oreoeca_, ii. 271

_Oreomanes_, ii. 278

_Oreonectes_, ii. 453

_Oreonympha_, ii. 108

_Oreoperdix_, ii. 338

OREOPHASINÆ, ii. 343

_Oreophasis_, ii. 343

_Oreophilus_, ii. 356

_Oreopyra_, ii. 107

_Oreortyx_, ii. 339

_Oreoscoptes_, ii. 256

_Oreothraupis_, ii. 99

_Oreotrochilus_, ii. 107

_Orestias_, ii. 450

Oriental region, defined, i. 75 subdivisions of, i. 75 description of, i. 314 zoological features of, i. 315 mammalia of, i. 315 birds of, i. 316 reptiles of, i. 317 amphibia of, i. 317 fresh-water fishes of, i. 318 summary of vertebrata of, i. 318 insects of, i. 318 sub-regions of, i. 321 concluding remarks on, i. 362 tables of distribution of animals of, i. 364

Oriental relations of W. African sub-region, i. 265

Oriental and Palæarctic faunas once identical, i. 362

Oriental and Ethiopian faunas, cause of their resemblances, i. 363

_Origma_, ii. 260

_Oriocalotes_, ii. 402

Orioles, ii. 268

ORIOLIDÆ, ii. 268

_Oriolus_, ii. 268

_Orites_, ii. 266

_Ornithion_, ii. 101

ORNITHORHYNCHIDÆ, ii. 253

_Ornithorhynchus_, ii. 253

_Orocætes_, ii. 256

_Orohippus_, N. American Tertiary, i. 136

_Ortalida_, ii. 343

_Orthagoriscus_, ii. 457

_Orthalicus_, ii. 516

ORTHIDÆ, ii. 532

ORTHOCERATIDÆ, ii. 506

_Orthodon_, ii. 452

_Orthogonius_, ii. 491

_Orthogonys_, ii. 98

_Orthonyx_, ii. 260

_Orthorhynchus_, ii. 108

_Orthotomus_, ii. 257

_Ortygometra_, ii. 352

_Ortygornis_, ii. 338

_Ortyx_, ii. 339

_Ortyxelos_, ii. 341

ORYCTEROPODIDÆ, ii. 246

_Orycteropus_, ii. 246

_Orycterus_, ii. 231

ORYGINÆ, ii. 223

_Oryx_, ii. 223

_Oryzoborus_, ii. 285

_Oryzorictes_, ii. 188

_Osmerus_, ii. 447

_Osphranter_, ii. 251

_Osteobrama_, ii. 453

_Osteochilus_, ii. 451

_Osteogeniosus_, ii. 443

OSTEOGLOSSIDÆ, ii. 454

_Osteoglossum_, ii. 454

_Ostinops_, ii. 282

OSTREIDÆ, ii. 533

_Ostrich_, Miocene of N. India, i. 162

Ostriches, ii. 368

_Otaria_, European Miocene, i. 118