{159}_Acineta_, Ehrb. (Fig. 61, 2); _Amoebophrya_, Koppen; _Choanophrya_, Hartog (Fig. 62); _Dendrocometes_, St. (Fig. 61, 4); _Dendrosoma_, Ehrb. (Fig. 61, 9); _Endosphaera_, Engelm.; _Ephelota_, Str. Wright (Fig. 61, 5, 8); _Hypocoma_, Gruber; _Ophryodendron_, Cl. and L. (Fig. 61, 7); _Podophrya_, Ehrb. (Fig. 61, 1); _Rhyncheta_, Zenker (Fig. 61, 3); _Sphaerophrya_, Cl. and L. (Fig. 61, 6), _Suctorella_, Frenzel; _Tokophrya_, Bütschli. This group, despite a superficial resemblance to the Heliozoa, show a close affinity to the Ciliata; the nuclear apparatus is usually double though a micronucleus is not always seen; the young are always ciliated, and the mode of conjugation is identical in all cases hitherto studied. Most of the genera are attached by a chitinous stalk (Fig. 61), continued in _Acineta_ into a cup or "theca" surrounding the cell. The pellicle is firm, often minutely shagreened or "milled" in optical section by fine radial processes, whether superficial rods or the expression of the meeting edges of radial alveoli is as yet uncertain. The pellicle closely invests the ectosarc, is continued down into a tubular sheath, from the base of which the tentacle rises, and upwards to invest the tentacle, and is even prolonged into its cavity in _Choanophrya_, the only genus where the tentacles are large enough for satisfactory demonstration. These organs may be one or more, and vary greatly in character. They may be (1) pointed for prehension, puncture, and suction (_Ephelota_, Fig. 61, 5); (2) nearly cylindrical, with a slightly "flared" truncate apex (_Podophrya_, Fig. 61, 1_a_); (3) filiform with a terminal knob; (4) "capitate" (_Acineta_, Fig. 61, 2); (5) bluntly truncate and capable of opening into a wide funnel for the suction of food[179] (_Choanophrya_, Fig. 62; _Rhyncheta_, Fig. 61, 3). Their movements, too, are varied, including retraction and protrusion, and a degree of flexion which reaches a maximum in _Rhyncheta_ (Fig. 61, 3), whose tentacle is as freely motile as an elephant's trunk might be supposed to be were it as slender in proportion to its length. They are continued into the body, and in _Choanophrya_ may extend right across it. In _Podophrya_ trold the pellicle rises into a conical tube about the base of the tentacle, which is retracted through it completely with the prey in deglutition. In _Dendrocometes_, _Dendrosoma_, and _Ophryodendron_ (Fig. 61, 4, 9, 7), the tentacles arise from outgrowths of the cell-body.