P AI 



PAL 



in others, the presence of oxygen ; in a 

 third class of terms, acuteness of sense 

 or function ; and, lastly, sharp-pointed- 

 ness. 



O'XYGEN (ofup, acid, yewao), to gene- 

 rate). The name given by Lavoisier to 

 an elementary body, with reference to its 

 property of forming acids vi^ith other ele- 

 mentary bodies. Oxygen is a permanent 

 gas, when uncombined, and forms one- 

 fifth part of the atmospheric air. By 

 Priestley it was called dephlogisticated 

 air ; by Scheele, empyreal air ; by Con- 

 dorcet, vital air. 



O'XYSTOMES (6fi«f, sharp, aTo/jia, a 

 mouth). The name given by Milne 



Edwards to the fourth and last family of 

 brachyurous crustaceans, comprising all 

 those species which most resemble the 

 type, especially in the conformation of 

 the buccal apparatus. 



O'ZON (o^o), to smell). The name 

 given by Schonbein to the odorous prin- 

 ciple emitted during the action of an 

 electrical machine. He considered it to 

 be a body contained both in air and in 

 water; that it had hitherto escaped the 

 observation of chemists ; and that, under 

 certain circumstances, it was set free by 

 electricity. It is probably a trit-oxide of 

 hydrogen. 



PACHYCEPHALI'NiE (Traxvc, thick, 

 K€<paXi], head). The name given, in 

 Mr. Swainson's classification of birds, to 

 the Great-headed Chatterers, the second 

 sub-family of the Ampelidae, or Chat- 

 terers. 



PACHYDE'RMATA (Traxir, thick, 

 iepfia, skin). An order of the Mammalia, 

 comprising thick-skinned animals, as the 

 elephant, the rhinoceros, &c., and certain 

 aquatic animals, approaching to the hip- 

 popotamus. 



PACKFONG. The white copper of 

 the Chinese, said to be an alloy of copper, 

 nickel, and zinc. It is also called Ger- 

 man Silver. 



PA'GINA. Literally, a page of a book ; 

 hence, applied to a surface of a leaf, 

 pagina superior being the upper, pagina 

 inferior the lower surface. 



PA'GODITE. A species of steatite or 

 serpentine, which the Chinese carve into 

 figures. 



PAGU'RIANS. A tribe of anomour- 

 ous crustaceans, named from the genus 

 pagurus, and known by the popular 

 names of Hermit-crabs and Soldier-crabs ; 

 in France they are called Bernards 

 I'Hermite. 



PAIRS, CHEMICAL. In the un- 

 organized kingdom the elementary sub- 

 stances are generally combined by the 

 force of affinity, either two and two in 

 pairs, or the pairs themselves forming 

 doublepairs, and in some few cases even 

 the double pairs united. In the organ- 

 ized kingdom, on the contrary, the four 

 elements do not enter into binary, but at 

 246 



least into ternary, or quaternary combi- 

 nations, without first forming pairs. 



PALiEO'GRAPHY {iraXaioi, ancient, 

 •Ypd(p<a, to write). The study of ancient 

 documents, including the knowledge of 

 the various characters used at different 

 periods by the writers and sculptors of 

 different nations and languages, their 

 abbreviations, initials, &c. 



PALiEONTO'LOGY {naXaio^, ancient, 

 ovra, beings, Xo^of, an account). The 

 science which treats of fossil remains, 

 both animal and vegetable; of their 

 forms and relations, of the changes which 

 they have undergone, and of the causes 

 which have produced their immersion in 

 the strata. 



PALiEOSAU'RUS (waXaio^, ancient, 

 cavpa, a lizard). The name of a genus 

 of fossil Saurians discovered in the mag- 

 nesian conglomerate on Durdham Down, 

 near Bristol, in 1834. 



PAL.aSOTHE'RIUM (TraXator, ancient, 

 6r\piov, a wild beast). A fossil extinct 

 quadruped, belonging to the order Pachy- 

 dermata, resembling a pig, or tapir, but 

 of great size. 



PALiEOZO'IC SERIES (TraXata ^wa, 

 ancient animals). A name given to the 

 fossiliferous strata of earlier geological 

 date than the carboniferous system, and 

 the mountain limestone, with reference 

 to their organic contents. The term 

 Protozoic has been applied to these early 

 groups of strata; but this term, it has 

 been observed, seems to assert more than 

 is necessary, perhaps more than is known. 



PALEA. Chaff: The term paleee is 



