PSILOMELANE. 504 PSORIASIS. monest of the mauganese uiinerals, with the possible exception oX pjrolusite. PSIT'TACI (Lat., parrots). The order or suborder of birds to which belong the parrots, parrakeets, love-birds, lorikeets, etc. (qq.v.). The Psittaci are easily recognized by the powerful hooked bill, cered at the base, the fleshy tongue, and the zygodactyl feet. The wings and tail are variable. " The furculum is weak, defective, or wanting; the lower larynx is peculiarly con- structed with three pairs of muscles: after- shafts are present on the feathers; and the pterylosis is remarkably falconiform. Coecum, gall-bladder, and soinetimes the oil-gland are wanting. The greatest diversity is shown in the arrangement of the carotid arteries and anibiens muscle. The classification of the Psit- taci has proved a puzzle, but there are probably at least two well-marked families, PsittacidiP and Trichoglossid*, with perhaps seven sub- families. PSKOV, pskuf. A government of Russia, bounded by the governments of Saint Petersburg and Novgorod on the north, Tver and Smolensk on the cast. Vitebsk on the south and southwest, and Livonia on the west (Map: Russia. C 3). Area. 17.070 square miles. The southern part is somewhat hilly and undulating: the northern is low, marshy, and thickly wooded. The chief rivers are the Lovat, which flows into Lake Ilmen ; the Velikaya, a tributary of Lake Pskov ; and the Diina, which drains the southeastern part of the government. Pskov has a large num- ber of lakes, of which Lake Pskov is the largest. The average annual temperature is about 41° F. Although the soil is mostly sandy and far from fertile, agrirulture is the chief industry, and rye and oats are the principal crops. On the larger estates, as well as on the farms owned by co!^n- ists from the Baltic Provinces, modern agricul- tural methods are employed, and cereals are raised for export. Stock-raising is neglected. Flax is grox^Ti on a large scale and exported. Next to agriculture, lumbering is the most important in- dustry. The principal manufacturing industries are distilling, milling, and the production of Imn- ber. The annual value of manufactures is over .$.5,000,000. Population, in 1897. 1.136.540. The bulk of the pupulation is composed of Great Russians. Ca])ital. Pskov. PSKOV. The capital of the government of the same name and one of the most ancient cities of Russia, situated on the rivers Velikaya and Pskova. 171 miles southwest of Saint Pe- tersburg (Map: Russia. C 3). It is divided into two parts, the Great City with the Krem- lin on the right bank of the Velikaya. and Zavelitchie on the opposite bank. The town is still partly surrounded by its ancient walls, and has retained snme remains of the fortress. In the old cathedral in the Kremlin dating from the twelfth centurv are the tombs of the princes of Pskov, and the church in the Spaso-Mirozhski Monasterv (twelfth century) contains well-pre- sered frescoes and mural paintings, and a treasury with many valuable antiquities. Note- worthv are also the Cathedral of Saints Peter and Paul with its ancient icons, the churches of the Old Ascension Convent, and the old palaces of the wealthy merchants. The modern town is uninteresting. The educational institutions of Pskov comprise two gmnasia, a Realschule, a corps of cadets, a seminary for teachers, and one for priests. There is a considerable trade and some manufacturing. Population, in 1897, 30,- 400. Pskov, ancient Pleskov, was in existence at the time of the coming of the Varangians to Russia. Threatened by the Lithuanians and the Germans, Pskov became a dependency of Nov- gorod, but, imlike other dependencies of that re- public, it enjoyed more or less autonomy, and its inhabitants took part in the rijctche of Novgorod (q.v. ). With the growth of its commerce Pskov became more and more independent, and finally began to elect its own princes, who, however, were still considered as representatives of Novgorod the Great. By the Treaty of Bolstov in 1348 Pskov attained complete independence. As a republic Pskov did not ditler essentially in its internal organization from Novgorod. Commercially it was of the utmost importance, lying on the way between Riga and Nov- gorod. In the fourteenth century it became a member of the Hanseatic League. The ag- gressive policy of the Princes of Moscow, however, soon put an end to the little re- ptiblic. Pskov committed the fatal blunder of appealing to the Princes of Moscow in its strug- gles with Novgorod in the beginning of the fifteenth century, thereby giving them an oppor- tunity to interifere in its internal affairs. The internal conflicts between the masses and the upper classes afforded Moscow an additional pretext for interfei;^nce, and Pskov was soon compelled to accept princes appointed by JIoscow. The position of Pskov was further weakened by the fall of Novgorod, and the republic was finally abolished in 1.510 by Prince Vasili. its riiefche suppressed, its leading merchants exiled to ilos- cow, and replaced by settlers from that city. Since then the city has declined, and the only important event in its history is its long siege by the Poles under Stephen Biithory in loSl-S2. Consult Nikitsty, Vmriss der innern Geschichtc Psk'ii:<< (Petersburg. 1873). PSKOV, L.KE. A lake in Russia. See Peipus. PSORALEA, so-rfi'le-a (Neo-Lat., from Gk. 'pupaX^os, psoraleos, scabby, from yj/dipa psorn. itch, from i/'Sk, psan, to rub; so called from the dot^ sprinkled over the surface). A genus of plant- of the natural order Legiuuinosfe, mostly natives of warm countries, with blue, purple, or white flowers, and generally abruptly pinnate leaver. Psoralea esculenta. the bread-root of North America, and prairie apple, pomme hlniichc and pomme dr prairie of the Canadian boatmen, is a perennial herb abotit a foot high, with a carrot- like root, rich in starch and used as food, both boiled and raw. It abounds on the high jilains from the Saskatchewan to Texas. Psornlca hfipoficpa and Psornlca cuspidnfa of the same region al«o have tuberous roots. PSORIASIS, sA-rl'a-sis (Neo-Lat.. from Gk. ^upi'oo-is, itcl*. from xf'upiS.v, psnrinn. to have the itch, from yf/iipa, psora, itch). Lepra , Alphos, A chronic skin disease characterized by inflamma- tory dry. red. roundish patches with adherent sil- very scales. Between the patches the skin cracks and bleeds. It is distributed principally over the extensor sides of the extremities, especially about the elbows and knees and the scalp, as also the trunk, and finally the flexor sides of the limbs.
