[Illustration: Fig. 51.--_Amphisia kessleri_.]


This variety differs from _O. kessleri_ as described by Wrzesniowski
in having three frontal cirri instead of four. Another difference
is in the structure of the nuclei and in their position. These
differences are too minute to warrant a specific name. _O. velox_ of
Quennerstedt is probably the same as _0. kessleri_, but differs in
having three complete rows of ventral cirri. _O. velox_ has three
frontal cirri in a line, thus differing from the Woods Hole form.


KEY TO THE MARINE GENERA OF EUPLOTIDÆ.

Diagnostic characters: Cilia, as well as the frontal, marginal, and
ventral cirri, very much reduced; the anal cirri, on the other hand,
are always present. The macronucleus is band-form.

1. Frontal cirri more than 8 2

Frontal cirri less than 8 3

2. Eleven marginal cirri on the left Genus _Certesia_
side; 11 frontal cirri

Four marginal cirri, 2 on each Genus *_Euplotes_
side; 9 to 10 frontal cirri

3. Seven frontal, 5 anal, 3 right Genus *_Diophrys_