_Experimental host._--_Periplaneta americana_, U.S.A. (Hegner, 1929): When fed to the insects in concentrated culture, _Euglena_ could withstand conditions in the crop up to 5 hours and were passed into the stomach in a viable state up to 6 hours. However, the majority were killed in the crop within 2 hours and very few reached the stomach alive. Order PROTOMONADINA Family OIKOMONADIDAE =Oikomonas blattarum Tejera= _Natural host._--Cockroach, Venezuela (Tejera, 1926). =Oikomonas= sp. _Natural host._--_Blatta orientalis_, U.S.S.R. (Yakimov and Miller, 1922): _Oikomonas_ sp. and _Monas_ sp. were found in the intestines of 83 percent of 124 cockroaches. Cockroach, Venezuela (Tejera, 1926). Family TRYPANOSOMATIDAE =Leptomonas blaberae= Tejera _Natural host._--_Blaberus_ sp., Venezuela (Tejera, 1926). =Leptomonas= sp. _Natural hosts._--_Parcoblatta lata_, _Parcoblatta pensylvanica_, _Parcoblatta virginica_, U.S.A., Ohio (Semans, 1939, 1941): Hind intestine. Of 70 specimens examined, 86 percent harbored _Leptomonas_ sp. * =Herpetomonas periplanetae= Laveran and Franchini _Natural host._--_Blatta orientalis_, Italy, France (Laveran and Franchini, 1920, 1920a). Family MONADIDAE =Monas= sp. _Natural host._--_Blatta orientalis_, U.S.S.R. (Yakimov and Miller, 1922): _Monas_ sp. and _Oikomonas_ sp. were found in the intestines of 83 percent of 124 cockroaches examined. Cockroach, Venezuela (Tejera, 1926). Family BODONIDAE =Bodo blattae= _Natural host._--_Blatta orientalis_, England (Lankester, 1865). =Bodo= sp. _Natural host._--_Blattella germanica_ and/or _Periplaneta americana_, South Africa (Porter, 1930). =Retortamonas blattae= (Bishop) _Synonymy._--_Embadomonas blattae_ Bishop [Wenrich, 1932]. _Natural host._--_Blatta orientalis_, England (Bishop, 1931): Hind intestine. The organism occurred in about 40 percent of the cockroaches examined. L. G. Feo (_in_ Wenrich, 1932) successfully cultured this protozoan (fig. 2, F). =Retortamonas= sp.? _Natural host._--_Leucophaea maderae_, Philippine Islands (Hegner and Chu, 1930).