[Illustration: Fig. 33.--_Lionotus fasciola_.]


KEY TO MARINE GENERA OF CHLAMYDODONTIDÆ.

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 striæ and cilia present, Genus _Orthodon_
ventral cilia longer