Part 9 (1/2)

1. _Gymnostomina_.

a. Mouth terminal or subterminal. Family _Enchelinidae_ Food is swallowed and not introduced by currents

b. Mouth terminal or subterminal; Family _Trachelinidae_ body frequently drawn out into long process; mouth may have specialized framework.

c. Mouth central or posterior; Family _Chlamydodontidae_ pharynx with supporting framework

2. _Trichostomina_.

a. Mouth anterior or central; Family _Chiliferidae_ pharynx short or absent; peristomial depression faint or absent

b. Mouth central; pharynx long, Family _Urocentridae_ tubular; cilia in two broad zones

c. Mouth posterior; form Family _Microthoracidae_ asymmetrical; cilia dispersed or limited to oral region

d. Mouth anterior or central. _Paramoecidae_ Peristomial depression (One genus, _Paramoecium_) clearly marked.

e. Mouth at end of long peristome Family _Pleuronemidae_ running along ventral side; body dorso-ventrally or laterally compressed; left edge of peristome with great, sail- like undulating membrane

f. Mouth and pharynx distinct, Family _Isotrichidae_ posterior; cilia uniform.

Parasites in ruminants.

g. Mouth absent; body vermiform, Family _Opalinidae_ cilia uniform. Usually parasites.

KEY TO MARINE GENERA OF ENCHELINIDae

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 a.n.u.s is usually terminal. Large food particles are swallowed, never introduced by currents.

1. Body naked 3

2. Body inclosed in a sh.e.l.l 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 _Chaenia_ flexible, and elastic

b. Mouth terminal; ”neck” highly Genus *_Lacrymaria_ elastic; entire body flexible; conical ”head”

c. Mouth terminal; ”neck” highly Genus *_Trachelocerca_ elastic; entire body flexible; ”head” square

d. Mouth terminal; ”neck” highly Genus _Lagynus_ elastic; no separate mouth-bearing portion

6. a. Body asymmetrical; bristles Genus _Stephanopogon_ in addition to cilia