Muller (1921:182) found maggots in a few eggs of a clutch, but thought that only the infertile and decomposing eggs were infested. I removed a hard, spherical cyst from the hind leg of a preserved softshell (TU). A captive hatchling (TU 17304) died as the result of a continuously enlarging and deepening hole on the top of its head; I could not discern a visible parasite with the naked eye. I found 25 leeches (_Placobdella parasitica_, largest about 13 mm.; identified by Dr. Kenneth B. Armitage, Department of Zoology, University of Kansas) in association with 11 _T. m. muticus_ (number per turtle not known) that were collected from the Kansas River at Lawrence, Douglas County, Kansas. Evermann and Clark (1920:596) reported a few nematodes in the stomachs of some _spinifer_, and three nematodes are listed by Harwood (1932:46, 60, 62, 66) in the same species. Hughes, Higginbotham and Clary (1941) have listed the known reptilian hosts of parasitic trematodes, and Hughes, Baker and Dawson (1941) have done the same for tapeworms. The species of parasites and their trionychid hosts are listed below. TREMATODA _Trionyx ferox_: _Neopolystoma orbiculare_ _Vasotrema amydae_ _Neopolystoma rugosa_ _Vasotrema attenuatum_ _Polystomoides coronatus_ _Vasotrema robustum_ _Teloporia aspidonectes_ _Trionyx muticus_: _Crepidostomum cooperi_ _Opisthorchis ovalis_ _Trionyx spinifer_: _Hapalorhynchus evaginatus_ _Vasotrema amydae_ _Opisthorchis ovalis_ _Vasotrema attenuatum_ _Polystomoides coronatus_ _Vasotrema longitestis_ _Teloporia aspidonectes_ _Vasotrema robustum_ CESTODA _Trionyx ferox_: _Proteocephalus trionychinus_ _Trionyx spinifer_: _Proteocephalus testudo_ NEMATODA _Trionyx spinifer_: _Camallanus trispinosus_ _Spiroxys amydae_ _Falcaustra chelydrae_ Economic Importance