| Macrostomum appendiculatum Fabricius, 1826 | Jul 1-Aug2, 1937 | | | slow flowing brook and bog pool in the surroundings of Laugarvatn, 1 specimen. |
| Gieysztoria oligocentra (Steinböck, 1948) | Jul 1-Aug2, 1937 | | | at the landing stage of the Gistihus, near hot springs, water with smell of sulfur, 22-27 degrees C, 1 specimen. |
| Gieysztoria cuspidata (Schmidt, 1861) | Jul 1-Aug2, 1937 | | | |
| Microdalyellia armigera (Schmidt, 1862) | Jul 1-Aug2, 1937 | | | in a slow flowing brook, a bog pool in surroundings of Laugarvatn, several specimens. |
| Castrella (Castrella) truncata (Abildgaard, 1789) | Jul 1-Aug2, 1937 | | | in a slowly flowing streamlet and in bog pools near Laugarvatn. |
| Castrada (Castrada) stagnorum Luther, 1904 | Jul 1-Aug2, 1937 | | | bog pool and brook moss surrounding Laugarvatn, Alptavatn and undrained cold and clear crater of lake Kerio east of Prastalundur. |
| Castrada (Castrada) inermis Hofsten N, 1911 | Jul 1-Aug 2, 1937 | | | clear streamlet issuing from a spring which empties slowly into Laugarvatn. |
| Castrada (Castrada) viridis Volz, 1898 | Jul 1-Aug 2, 1937 | | | slow flowing clear brook issuing from a spring and emptying into Laugarvatn, 2 specimens. |
| Castrada (Castrada) affinis Hofsten N, 1907 | Jul 1-Aug 2, 1937 | | | bog pool north of Laugarvatn, 1 specimen. |
| Bothromesostoma personatum (Schmidt, 1848) | Jul 1-Aug 2, 1937 | | | bog pool north of Laugarvatn, 1 specimen. |
| Geocentrophora baltica (Kennel, 1883) | Jul 1-Aug 2, 1937 | | | slowly flowing clear brook issuing from a spring near Laugarvatn. |
| Otomesostoma auditivum (Forel & du Plessis, 1874) | prior to Aug 1937 | | | Author received material collected by Danish zoologists. |
| Otomesostoma auditivum (Forel & du Plessis, 1874) | Jul 1-Aug 2, 1937 | | | pools near Laugarvatn |
| Microstomum sp. Steinböck, 1948 | summer 1937 | | | Many specimens. |