PLESIOSAURUS, technically the name of a genus of extinct reptiles of the group Sauropterygia ; it is commonly used to apply to all the later members of that group. The typical plesiosaurs are completely adapted for a marine existence in the open sea.
large part in Lenin's early mental development. In the '9os and the early years of the 2oth century the two men were closely asso ciated. In Dec. 1900 was founded the S.D. journal Iskra (The Spark) of which Plekhanov was joint editor with Lenin, Martov, and others. In the first split of the Russian S.D. Party in 1903 Plekhanov was largely on the side of the Bolsheviks, holding views closely akin to those of Lenin.
After the resignation of the Mensheviks from editorship of the Iskra Plekhanov and Lenin were joint editors, but some months later differences arose between them on the question of collaboration with the Mensheviks, and Lenin resigned. Thence forth for several years Plekhanov worked with the Menshevik section of the party, but after 1907, while remaining a Menshevik, he took up an attitude on many issues, particularly on the ques tion of participation in the State Duma and also on illegal activi ties, in agreement with that of the Bolsheviks. At the end of
1910 he again co-operated with the latter in contributing to the Bolshevik Zviezda (The Star) but the alliance did not last long, and when the war broke out in 1914 Plekhanov was foremost in advocacy of the principle of "revolutionary defence" of the country against the Bolshevik policy of working for the defeat of the Government. After the March revolution he returned to Russia and was invited to join the Provisional Government. He refused, but actively supported the Government against the Bolsheviks, and remained an opponent of the Bolshevik revolu tion until his death in Finland on May 30, 1918.
Plekhanov had an enormous influence on the development of the Socialist movement in Russia. The Moscow Marx-Engels Institute has published a complete edition of his works in 26 volumes. His biggest work is available in German: Beitrage zur Geschichte des Materialismus.