| Macrostomidae | Archimacrostomum | Ferguson, 1954 | |
| Macrostomidae | Axia | Ferguson, 1954 | |
| Macrostomum | beauchampi | Ferguson, 1939 | |
| Macrostomum | beaufortense | Ferguson, 1937 | |
| Archimacrostomum | beaufortense | (Ferguson, 1937) | |
| Pregermarium | beaufortensis | Stirewalt, Ferguson, & Kepner, 1942 | |
| Macrostomum | beaufortensis | Ferguson, 1937 | |
| Macrostomum | tuba | bulbostylum | Ferguson & Jones, 1940 |
| Macrostomum | carolinense | Ferguson, 1940 | |
| Macrostomum | ruebushi | carolinensis | Ferguson, 1940 |
| Pregermarium | carolinensis | Stirewalt, Ferguson, & Kepner, 1942 | |
| Macrostomum | collistylum | Ferguson, 1939 | |
| Macrostomum | ruebushi | crenatostylum | Ferguson, 1940 |
| Macrostomum | curvistylum | Ferguson, 1939 | |
| Plagiostomum | dahlgreni | Kepner,Stirewalt &Ferguson, 1941 | |
| Macrostomum | ruebushi | finnlandense | Ferguson, 1940 |
| Macrostomum | finnlandense | (Ferguson, 1940) | |
| Macrostomum | appendiculatum (1) | finnlandensis | Ferguson, 1940 |
| Macrostomum | ruebushi | finnlandensis | Ferguson, 1940 |
| Macrostomum | frigorophilum | (Ferguson, 1940) | |
| Macrostomum | ruebushi | frigorophilum | Ferguson, 1940 |
| Axia | gieysztori | (Ferguson, 1939) | |
| Macrostomum | gieysztori | Ferguson, 1939 | |
| Promacrostomum | gieysztori | (Ferguson, 1939) | |
| Macrostomum | gilberti | Ferguson, 1939 | |
| Macrostomum | glochistylum | Ferguson, 1939 | |
| Macrostomum | glochostylum | Ferguson, 1939 | |
| Macrostomum | glocostylum | Ferguson, 1939 | |
| Macrostomum | graffi | Ferguson, 1939 | |
| Macrostomum | granulophorum | Ferguson, 1940 | |
| Macrostomum | ruebushi | granulophorum | Ferguson, 1940 |
| Macrostomidae | Inframacrostomum | Ferguson, 1954 | |
| Karlingiinae | Karlingia | Ferguson, 1954 | |
| Macrostomum | ruebushi | kepneri | Ferguson & Jones, 1940 |
| Macrostomum | kepneri | (Ferguson & Jones, 1940) | |
| Polycystidinae | Klattia | Kepner, Stirewalt & Ferguson, 1939 | |
| Macrostomum | lewisi | Ferguson, 1939 | |
| Jensenia | lewisi | Jones & Ferguson, 1948 | |
| Halammovortex | lewisi | (Jones & Ferguson, 1948) | |
| (Castrada) | lutheri | Kepner, Stirewalt & Ferguson, 1939 | |
| Macrostomum | norfolkense | Jones & Ferguson, 1940 | |
| Macrostomum | norfolkensis | Jones & Ferguson, 1940 | |
| Macrostomum | ontarioense | Ferguson, 1942 | |
| Promacrostomum | paradoxicum | Ferguson, 1954 | |
| Phonorhynchus | pearsei | Ferguson, Stirewalt & Kepner, 1940 | |
| Macrostomum | phillipsi | Ferguson & Stirewalt, 1938 | |
| Cylindrostomidae | Pregermarium | Stirewalt, Ferguson, & Kepner, 1942 | |
| Pseudostomidae | Pregermarium | Stirewalt, Ferguson, & Kepner, 1942 | |
| Trigonostomum | prytherchi | Kepner, Ferguson & Stirewalt, 1941 | |
| Macrostomum | recurvostylum | Ferguson, 1940 | |
| Macrostomum | ruebushi | recurvostylum | Ferguson, 1940 |
| Macrostomum | reynoldsi | Ferguson, 1939 | |
| Macrostomum | riedeli | Ferguson, 1940 | |
| Macrostomum | ruebushi | Ferguson, 1940 | |
| Macrostomum | schmitti | Hayes & Ferguson, 1940 | |
| Macrostomum | ruebushi | schmitti | Hayes & Ferguson, 1940 |
| Macrostomum | shenandoahense | Ferguson, 1940 | |
| Macrostomum | ruebushi | shenandoahensis | Ferguson, 1940 |
| Macrostomum | appendiculatum (1) | sillimani | Ferguson, 1939 |
| Geocentrophora | sp. | Ferguson et al., 1939 | |
| Tauridella | sp. | Ferguson & Jones, 1949 | |
| Typhloplana | sp. | Ferguson, Stirewalt, Brown & Hayes, 1939 | |
| Trigonostomum | sp. | Ferguson & Jones 1949 | |
| Proxenetes | sp. | Ferguson & Jones, 1949 | |
| Monochoerus | sp. | Ferguson & Jones, 1949 | |
| (Karkinorhynchus) | sp. | Ferguson & Jones, 1949 | |
| Dalyellia | sp. | Ferguson & Jones, 1949 | |
| Vejdovskya | sp. | Ferguson & Jones, 1949 | |
| Baicalellia | sp. | Ferguson & Jones, 1949 | |
| Monocelis | sp. | Ferguson & Jones, 1949 | |
| Prorhynchus | sp. | Ferguson & Jones 1949 | |
| Stenostomum | sp. | Ferguson & Jones, 1949 | |
| Rhynchoscolex | sp. | Ferguson & Jones 1949 | |
| Catenula | sp. | Ferguson & Jones, 1949 | |
| Aphanostoma | sp. | Ferguson & Jones, 1949 | |
| Karkinorhynchus | sp.1 | Ferguson & Jones, 1949 | |
| Macrostomum | appendiculatum (1) | stirewalti | Jones & Ferguson, 1941 |
| Macrostomum | tennesseense | Ferguson, 1940 | |
| Macrostomum | ruebushi | truncatum | Ferguson, 1940 |
| Macrostomum | truncatum | Ferguson, 1940 | |
| Macrostomum | vejdovskyi | Ferguson, 1940 | |
| Mesostoma | virginianum | Kepner, Stirewalt & Ferguson, 1939 | |
| Macrostomum | virginianum | Ferguson, 1937 | |
| Klattia | virginiensis | Kepner, Stirewalt & Ferguson, 1939 | |
| Archiloa | wilsoni | Stirewalt, Kepner & Ferguson, 1940 | |
| Promonotus | wilsoni | (Stirewalt, Kepner & Ferguson, 1940) |
86 names, including those in new combination. (Max listing set to 900)