Key to families of Suctoria.
a. Unattached forms; ventral cilia present; one suctorial tentacle Hypocomidæ
b. Attached forms; thecate and athecate tentacles simple, one or two in number Urnulidæ
c. Thecate; posterior end of cup drawn out into stalk; walls perforated for exit of tentacles Metacinetidæ
d. Stalked or unstalked; globular; tentacles of different kinds, some knobbed, others pointed Podophryidæ
(2 genera
*[Ephelota], *[Podophrya)]
e. Naked or thecate; stalked or not; tentacles numerous, usually knobbed and all alike Acinetidæ
f. Naked; athecate; tentacles numerous, all alike, knobbed and grouped in tufts. They may be simple or branched. Dendrosomidæ
g. Sessile forms resting on basal surface or on a portion raised like a stalk; tentacles many; short and knobbed; distributed on apical surface or localized on branched arms Dendrocometidæ
h. Stalked or sessile; tentacles long, rarely knobbed, supported on proboscis-like processes Ophryodendridæ
* Presence at Woods Hole indicated by asterisk.

Genus PODOPHRYA Ehr. '33.

(Bütschli '88; Stein '59; Perty '52; Cienkowsky '55;
Quenn. '69; Hertwig '77; Maupas '81.)


Fig. 65.—
Podophrya gracilis.
[ ENLARGE ]

The body is globular, with tentacles radiating in all directions. The tentacles may be very short or very long. The stalk also is either short or long, and some species form stalks but rarely (P. libera). The macronucleus is centrally placed and globular to ovoid in form. The contractile vacuole is usually single. Reproduction takes place by division; the distal half developing cilia and becoming a swarm-spore. Fresh and salt water.

Podophrya gracilis, n. sp. Fig. 65.

Of all the Podophrya that have been described not one approaches this minute form in the relative length of the stalk. The body is spherical and is covered with short capitate tentacles. The stalk is extremely slender, bent, and without obvious structure. There are one or two contractile vacuoles in the distal half of the body. The nucleus is small and is situated near the insertion-point of the stalk. Reproduction not observed. Diameter of body 8µ; length of stalk 40µ. Only one specimen seen.