SUMMARY
Descriptive notes are given for the following species of Pythiumrecovered from soil and water in various localities in Iceland: P. debaryanum, P. dissotocum, P. echinulatum, P. gracile, P. inflatum, P. mamillatum, P. middletonii, P. monospermum, P. pulchrum, P. rostraturn, P. tenue, P. torulosum, P. ultimum, P. undulatum, and P. vexans. A form of P. tenue is reported as a possible intermediate between this species and P. gracile, and a species (of the filamentous sporangiate series) lacking an antheridial apparatus is described but not named.