rows of cilia and trichocysts. Under the microscope this is one of
the most pleasing forms found at Woods Hole. Its color is yellowish
brown from the presence of brilliant particles of coloring matter
held in the cortical plasm, and, as it slowly rolls along, these
particles and the black trichocysts give to the organism a peculiar
sparkling effect. The macronucleus is almost central; the contractile
vacuole posterior. The endoplasm appears well filled with food
bodies, some of which could be distinguished as _Amphidinium_ and
_Glenodinium_.

Length 55 mu; greatest diameter 30 mu.

[Illustration: Fig. 34.--_Nassula microstoma_.]

Genus CHILODON Ehr.

(Dujardin '41; Engelmann '78; Stein '54, '58; Kent '81; Buetschli '88;
Gruber '83; Cienkowsky '55; Moebius '88; Clap. et Lach '58;
Wrzesniowksi '65; Shevyakov '96.)

Small forms, greatly flattened dorso-ventrally and almost egg-form in
outline. The anterior end is bent distinctly to the left and forms a
characteristic process, which, together with the entire margin of the
body, is soft and flexible. The posterior end is, as a rule, broadly
rounded. The ventral surface is finely striate, and this surface
alone is ciliated. The lines of cilia converge at the mouth, and at
this region the cilia are somewhat larger and more distinct, thus
forming a functional adoral zone. The mouth is median and is situated
in the anterior half of the body. It is surrounded by a well-defined
armature, composed usually of from 10 to 16 rods. The contractile
vacuoles are quite varied and from one to many in number, the
number increasing with the size of the individual. The macronucleus
is usually single, elliptical in form, and centrally placed;
one micronucleus. Reddish granular pigment and trichocysts are
occasionally present.

Chilodon cucullulus Muell., sp. Fig. 35.

Synonyms; _Colpoda cucullus_ O. F. Mueller; _Loxodes cucullulus_;
_Chilodon uncinatus_ Ehr. '58, Perty '52, Dujardin '41; _L. dentatus_
Duj., etc.

This extremely variable form has received so many different names
that it hardly pays to enumerate them. It is one of the commonest
and most widely spread ciliates known, although at Woods Hole I was
surprised to see it so rarely. It is the type species of the genus
and needs no further description. The specimens observed at Woods
Hole had numerous contractile vacuoles and were 42 to 45 mu long and
from 28 to 32 mu wide.

[Illustration: Fig. 35.--Ventral and dors