Etude au Microscope Electronique du CiliéPseudomicrothorax dubius Maupas

SYNOPSIS. Ciliates of the genus Pseudomicrothorax present, at the ultrastructural level, some remarkable peculiarities from the points of view of both cytology and taxonomy. The trichocysts have 4 apical blades which are characteristic of the family Microthoracidae; the curious subcuticular membrane is found in the Microthoracidae and, admittedly less typically, in the Nassulidae; the cytopharyngeal armature is exactly comparable to that of the Nassulidae. These facts, like those of Thompson and Corliss on the organization of the oral ciliates, show—as suggested by Corliss–that the taxonomic position of the genus Pseudomicrothorax throws light on certain stages of the evolution of the Ciliata.