Page:The American Cyclopædia (1879) Volume XIII.djvu/630

 610 PLESKOV PLEURISY lichodeirus (Conyb.), which attained a length of 10 to 12 ft. ; there were about 50 teeth in each jaw ; the neck was as long as the body and tail together, having 33 vertebrae, 10 more than the longest neck of a bird ; the ribs were uni- ted in front by several cartilages, enabling the animal to inflate the lungs readily and fully, and take in a supply of air for a prolonged im- mersion ; the coracoid bones were very large, producing an elongation of the sternum, and indicating that the animal was aquatic, and Skeleton of Plesiosaurus. able only with difficulty to drag itself along on land. The less strong and less numerous teeth show a less carnivorous disposition than in the ichthyosaurus ; the slighter general conforma- tion was suited rather for tranquil waters than to encounter powerful waves. Species are found also in the oolite and cretaceous strata, though less abundantly than in the lias, in which their numerous remains and coprolites show that the waters must have swarmed with them. For full details on the species, see Owen's " Report on British Fossil Reptiles," in " Reports of the British Association " for 1839. The genus pliosaurus (Owen) includes the gigantic reptiles of the Oxford and Kim- meridge clays of England, intermediate be- tween the plesiosaurus and the ichthyosaurus ; the teeth and the bones of the limbs and trunk were like those of the former, the first being stouter and more trenchant ; but they had the short neck, massive head, and cetacean-like form of the latter genus. It is interesting to note that pliosaurus did not appear until after both the genera which it in part resembles ; no fragment of their bones, according to Pic- tet, has been found in the lias or oolite, and none until the time of the Oxford clays. The best known species is the P. IracJiydeirus (Owen), for an account of which see Owen's report in " Reports of the British Association " for 1841. PLESROV. See PSKOV. PLESSIS, Joseph Octave, a Canadian bishop, born in Montreal, March 3, 1762, died in Que- bec, Dec. 4, 1825. He was ordained priest in Quebec March 11, 1786, and became secretary to the bishop and rector of the cathedral. Elected coadjutor to Bishop Denaud Sept. 6, 1797, the captivity and death of Pius VI. pre- vented the ratification of his choice at Rome till April 28, 1800, when he was confirmed with the title of bishop of Canata. His elec- tion by the church of Canada and his confir- mation by the pope gave rise to a long contro- versy with the British government. The kings of France had exercised the right of presenta- tion to all bishoprics, as well as that of con- firming the election of bishops when made by the local clergy. The same right was claimed by the English crown after the conquest of Canada; but the claim was strenuously and successfully resisted by Bishop Plessis. He was consecrated in Quebec, Jan. 25, 1801, and became titular bishop Jan. 17, 1806. In 1818 he was appointed by the crown a member of the legislative council of Canada. After becoming titular bishop he raised the standard of learn- ing in the existing col- leges, founded at his own expense the college of Nicolet, and multi- plied primary schools. He also displayed great zeal in providing for the spiritual wants of the Indians, and made several fruitless attempts to obtain the recall of the Jesuits and other missionaries. In 1819 he visited London and Rome for the purpose of having British North America organized into an ecclesiastical prov- ince, with an archbishop at Quebec and suffra- gan bishops in the principal cities and mission- ary centres; but he only succeeded in having auxiliary bishops appointed for Montreal, Hali- fax, and the Indian missions of the Red River district. He left several pastoral letters, a col- lection of Latin synodal addresses, and a man- uscript journal of his journey to Europe. See J. B. A. Ferland's "Life of Bishop Plessis.'.' PLESSIS-MARLY, Seigneur dn. See MORNAY. PLETHO. See GEMISTUS. PLEURA (Gr. TrAevpa, the side), the thin se- rous membrane which lines the cavity of the chest on either side, and is reflected at the root of the lung over the external surface of these organs. That portion of the pleura which lines the wall of the chest is called the costal pleura, and that which covers the lung the pulmonary pleura. The space between the two is the pleural cavity. In the healthy con- dition, however, this cavity can hardly be said to exist, since the two opposite surfaces of the pleura, though not adherent, are in contact with each other, or separated only by an ex- tremely thin layer of serous fluid, which ena- bles them to glide readily over each other in the movements of respiration. (See LUNGS, and THORAX.) In disease the pleural cavity on either side is liable to be distended by an exudation of serum or of pus, or sometimes of air which gains access from a wound of the lung or of the walls of the thorax. The pleural surfaces may also become adherent to each other, as a consequence of inflammation, thus obliterating more or less completely the pleural cavity, and interfering with the free action of the lung. PLEURISY (pleuritis), inflammation of the pleura, the membrane which lines the chest, and also covers the lungs. Pleurisy has been