the body, the other longitudinal upon the face only. The shell is
soft and structureless with a distinct aperture near the meeting
point of the two furrows. The endoplasm usually, but not always,
contains a bright red eye-spot.

Fresh and salt water.


Glenodinium compressa, n. sp. Fig. 21, a, b, c.

This species resembles _G. acuminata_ of Ehrenberg except that it is
strongly compressed laterally. The longitudinal furrow extends nearly
to the extremity of the animal. It begins as a narrow slit and widens
as it progresses upon the left side; it also becomes much deeper
on this side and at the bottom of the depression the longitudinal
flagellum is inserted. The transverse furrow runs evenly around the
body near the upper pole, giving to the shell almost the aspect of
an _Amphidinium_. Brown chromatophores may or may not be arranged
radially about a central amylum granule. One striking characteristic
is the depth of the two furrows. The nucleus is elongate and somewhat
curved; it lies against the posterior wall of the rather thick shell.
Not uncommon.

Length 40µ; breadth 32µ; width 18µ.

The posterior end of the animal is often somewhat pointed and this
point frequently becomes attached, so that the animal whirls around
upon it as upon a pivot.