76 GLOSSARY. 



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 ser- 

 pents. Etym., o0te, ophis, a serpent. 



ORGANIC REMAINS. The remains of animals and plants; organized 

 bodies, found in a fossil state. 



ORTHOCERATA. An extinct genus of the order of Molluscous Ani- 

 mals, called Cephalopoda, that inhabited a long chambered, 

 conical shell, like a straight horn. Etym., opdos, orthos, straight, 

 and Kepct, ceras, horn. 



OSSEOUS BRECCIA. The cemented mass of fragments of bones of 

 extinct animals found in caverns and fissures. Osseus is a Latin 

 adjective, signifying bony. 



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. 



OXYGEN. One of the constituent parts of the air of the atmosphere ; 

 that part which supports life. For a further explanation of the 

 word, consult elementary works on chemistry. 



OXIDE. The combination of a metal with oxygen ; rust is oxide of 

 iron. 



PACHYDERM ATA. An order of quadrupeds, including the elephant, 



rhinoceros, horse, pig, &c., distinguished by having thick 



skins. Etym. WUQ, pachus, thick, and <5ep/ia, derma, skin or 



hide. 



PACHYDERMATOUS. Belonging to pachydermata. 

 PALJSOTHERIUM, PALEOTHERE. A fossil extinct quadruped, belonging 



to the order pachydermata, resembling a pig or tapir, but of 



great size. Etym. iraXaioe, palaios, ancient, and drjpiov, therion, 



wild beast. 

 PELAGIAN, PELAGIC. Belonging to the deep sea. Etym. pelagus, 



sea. 

 PEPERINO. An Italian name for a particular kind of volcanic rock, 



formed, like tuff, by the cementing together of volcanic sand, 



cinders, or scoriae, &c. 

 PETROLEUM. A liquid mineral pitch, so called because it is seen 



to ooze like oil out of the rock. Etym. petra, rock, and oleum, 



oil. 

 PHANEROGAMIC PLANTS. A name given by Linnaeus to those plants 



