Opalized Wood. Wood petrified by siliceous earth, and acquiring a structure similar to the simple mineral called opal.
Ophidious Reptiles. Vertebrated animals, such as snakes and serpents. Etym., οφις, ophis, a serpent.
Organic Remains. The remains of animals and plants (organized bodies) found in a fossil state.
Orthocerata or Ohthoceræ. An extinct genus of the order of molluscous animals, called Cephalopoda, that inhabited a long-chambered conical shell, like a straight horn. Etym., ορθος, orthos, straight, and κερας, ceras, horn.
Osseous Breccia. The cemented mass of fragments of bones of extinct animals found in caverns and fissures. Osseous is a Latin adjective, signifying bony.
Osteology. That division of anatomy which treats of the bones; from οστεον, osteon, bone, and λογος, logos, a discourse.
Outliers. When a portion of a stratum occurs at some distance, detached from the general mass of the formation to which it belongs, some practical mineral surveyors call it an outlier, and the term is adopted in geological language.
Ovate. The shape of an egg. Etym., ovum, egg.
Ovipositing. The laying of eggs.