| Macrostomum sensitivum Silliman, 1884 | 1915-1917 |  |  | pond. | 
| Mesostoma angulare Higley, 1918 | 1915-1917 |  |  | from the Illinois River at Havana. | 
| Prorhynchus applanatus Kennel, 1888 | 1915-1917 |  |  | Collected during the month of February, 'from under ice, individuals of this species appeared crawling in masses of Cladophora. | 
| Typhloplana viridata (Abildgaard, 1789) | 1915-1917 |  | algae | taken from algae close to the bottom in April and occasionally in the summer and fall.  Many individuals. | 
| Gyratrix hermaphroditus Ehrenberg, 1831 | 1915-1917 |  | algae | July.  Frequent 'in nearly all of the collections made from the many sloughs and overflow waters along the Illinois river.' | 
| Macrostomum album Higley, 1918 | 1918 or earlier |  |  | ponds near Havana. |