(right) side, with, however, a row of large cilia marking the course of the elongate mouth, upon its left side.  The right side is striated, the left arched and without markings.  The endoplasm is finely granular with, however, larger food particles in the process of digestion, while specimens are occasionally seen with the natural form completely lost through distortion caused by over-large captures (Cf. also Wrzesniowski ’70, p.  XXIII, fig. 32).  Movement continuous, slow, and gliding; very little tendency to jerking movements.  Macronucleus double, both parts spherical, and placed in about the center of the larger part of the body; closely approximated but not, as Schewiakoff described, connected.  In conjugation, a large form unites with a smaller one, the mouth parts being connected.  Details of conjugation and macronuclei not made out.  Length 200 mu to 600 mu.

[Illustration:  Fig. 33.—­Lionotus fasciola.]

KEY TO MARINE GENERA OF CHLAMYDODONTIDAE.

Diagnostic characters:  Form usually ellipsoid, never very elongate.  Transverse section of body circular or elliptical.  The mouth is usually some distance from the anterior end and may be in the posterior part.  Sometimes it is in the center of the ventral surface, again on the right side.  The oesophagus invariably has a well-developed buccal armature, or a smooth peculiarly built oesophageal tube.  Food particles of large size.

1.  Body cylindrical.  Cilia about Genus *_Nassula_
   entire body

   Body flat 2

2. a.  Without a caudal process 3

   b.  With a caudal process 5

3. a.  Anterior end angular 4
      on left side

   b.  Anterior end rounded Genus Chlamydodon

4. a.  Dorsal striae and cilia present, Genus Orthodon
      ventral cilia longer

   b.  Dorsal striae and cilia absent; Genus *_Chilodon_
      posterior end not pointed

   c.  Dorsal striae and cilia absent; Genus Scaphidiodon
      posterior end pointed

5. a.  Caudal spine with posterior 6
      bristle-like cilia

   b.  Caudal spine without posterior Genus Trochilia
      bristle-like cilia;
      ventral cilia reduced

6. a.  With pigment spot on anterior Genus AEgyria
      angle

   b.  Without such pigment spot Genus Onychodactylus

   c.  Cilia on right edge only of Genus *_Dysteria_
      greatly reduced ventral surface

   * Presence at Woods Hole indicated by asterisk.

Genus NASSULA Ehr. ’33

(Dujardin ’41; Stein ’67; Cienkowsky ’55; Cohn ’66; Clap. et Lach. ’58; Kent ’81; Maupas ’83; Entz ’84; Fabre-Domergue ’88; Buetschli ’88; Shevyakov ’96.)