KEY TO MARINE GENERA OF ENCHELINIDÆ

Diagnostic characters: Form ellipsoid or ovoid; the mouth is
invariably terminal and is usually round--more rarely slit-formed; it
is closed except when food is taken. An oesophagus when present is a
short, invariably non-ciliated tube which is usually surrounded by
a more or less clearly defined buccal armature. The anus is usually
terminal. Large food particles are swallowed, never introduced by
currents.

1. Body naked 3

2. Body inclosed in a shell or coat 7

3. a. Cilia uniform about the entire 4
body; body symmetrical

b. Cilia in the mouth region 5
longer than the others; body
symmetrical

c. Bristles, or tentacles, in 6
addition to cilia

4. Mouth terminal; body ellipsoidal Genus _Holophrya_
to ovoid

5. a. Mouth terminal; body elongate, Genus _Chænia_
flexible, and elastic