On two new species of genus Lineus (Heteronemertini) and the origin of two lobes on the posterior end of the body of nemerteans [O dvukh novykh vidakh Lineus (Heteronemertini) i proiskhozhdenii dvulopastnogo zadnego kontsa tela u nemertin] - Korotkevich, V. S. (Issledovaniia Fauny Morei, 1977)