a. From 40 waters of the Abisko-district (Sweden, Lapland) 58 samples were collected (essentially samples from sediments). b. It is not possible to clear the origin of all discovered tests of sediments. The bottom of most waters was covered with mosses, from which vegetation, tests can come into the sediments. But also tests from other biotopes, can be found at the bottom. c. Nevertheless we can recognize typical characters of those species living in sediments. The prevalent type is the “Difflugia-type”. Those species of Centropyxis which immigrated into sediments demonstrate a trend towards the “Difflugia-type”. The immigration is possible from Aufwuchs, mosses and soils. 62,7% of the recorded tests belong to Difflugia, 17,8% to Centropyxis. d. The prevalent species in the sediments of the Abisko-district is Difflugia elegans var. teres, the next is D. glubolosa. e. A great number of investigated waters contained the oligotrophic species Centropyxis aërophila. Only one lake (Ruontenjaure) shows the association of dystrophic lakes. f. Some species are described taxonomically, for instance: Centropyxis nauwercki n.sp. C. nauwercki is very much like Difflugia, but is also connected with C. platystoma. The new species shows a trend from Centropyxis to Difflugia. g. C. aërophila can also immigrate into the Aufwuchs. There the species has membraneous tests. h. Geographical aspects of the sediment colonization are discussed.