A Dinoflagellate with Characters of Gymnodinium and Gyrodinium*

SYNOPSIS. An organism was isolated which in the first instance appeared to be Gymnodinium mirabile and in subsequent cultures took on characteristics similar to those of Gyrodinium fissum. It is not known at present whether the pleomorphism exhibited by this strain is frequent among the naked flagellates, but this finding raises the question of whether naked dinoflagellates can be identified by examination of collected samples, whether living or preserved, or whether culture studies are necessary for all such identifications.