Common in decaying algæ. Length 60µ; greatest diameter 30µ.


[Illustration: Fig. 16.--Two aspects of _Astasia contorta_.]


Genus ANISONEMA Bütschli

Flagellates with two flagella, of which one is directed forwards and
is concerned with the locomotion of the animal, while the other is
directed backwards and drags after the animal when in motion. Body
slightly compressed dorso-ventrally (fig. 17, section). An oral
furrow is present on the ventral side and the two flagella originate
in it (fig. 17, at left). The vacuole is on the left side. Food
vacuoles are present in the posterior part. The nucleus is central.
Movement creeping.

Fresh and salt water.


Anisonema vitrea (Duj.) Fig. 17.

Synonyms: _Tropidoscyphus octocostatus_ Stein '83; _Sphenomonas_ Kent
'81; _Ploeotia vitrea_ Senn 1900.

With the characteristics of the genus. It differs from freshwater
forms in having eight furrowed surfaces running somewhat spirally
from the posterior to the oral end. Length 50µ; width 23µ. This
attractive flagellate was quite common in decaying algæ at Woods
Hole; its shaking movement, its peculiar furrowed surfaces, and,