e observers deny this
(_e.g._ Maupas). Others describe them on the dorsal side of the
posterior end (Quennerstedt). The macronucleus is long and beaded and
placed upon the right side. Micronuclei are numerous and scattered
along the macronucleus. The anus is terminal and dorsal. Food
consists of large and small particles. Movement rapid, free swimming,
alternating with resting periods; in some cases an undulating or
wriggling movement is seen, showing clearly the flexibility of the
body. Fresh and salt water.

Condylostoma patens Mueller. Fig. 45.

The body is elongate, somewhat sac-like, five or six times as long
as broad, plastic, and frequently contains brightly colored food
granules. The triangular peristome takes up the greater part of the
anterior end, and the mouth is situated at the sharper angle of the
triangle, about one-fourth of the total length from the anterior end.
The cuticle is longitudinally striated, the lines having a slightly
spiral course. They are not closely set, and fine cilia are thickly
inserted along their edges. The endoplasm is granular and viscous.
The motile organs consist of an adoral zone of membranelles, which
stretch along the left edge of the peristome and the front edge of
the body. The right edge of the peristome supports an undulating
membrane. The nucleus is moniliform and extends the full length of
the left side; a number of micronuclei are distributed along its
course (Maupas).

Length 400 mu; diameter at widest part 105 mu. Maupas gives the length
from 305 mu to 495 mu; and Stein 376 mu to 564 mu. Very common.

For a more extended account of the structures, see the excellent
description by Maupas '83.

[Illustration: Fig. 45.--_Condylostoma patens_.]

KEY TO THE MARINE GENERA OF STENTORIDAE.

Diagnostic characters: The peristome is relatively short and limited
to the front end of the animal, so that its plane is nearly at right
angles to that of the longitudinal axis of the body. The adoral zone
of cilia either passes entirely around the peristome edge or ends at
the right-hand edge. The surface of the peristome is spirally
striated and provided with cilia. Undulating membranes are absent.

1. Peristome circular in outline; Genus _Stentor_
limited to the anterior end

2. The peristome is drawn out into two Genus _Folliculina_
wing-like processes; tube-dwelling

Genus STROMBIDIUM Cl. & Lach. '58.

(Stein '67; Buetschli '73; Fromentel '74