2. Eleven marginal cirri on the left Genus _Certesia_
side; 11 frontal cirri
Four marginal cirri, 2 on each Genus *_Euplotes_
side; 9 to 10 frontal cirri
3. Seven frontal, 5 anal, 3 right Genus *_Diophrys_
marginal, and 2 left marginal
cirri
No frontal, 5 anal, 3 right, Genus *_Uronychia_
and 2 left marginal cirri
* Presence at Woods Hole indicated by asterisk.
Genus EUPLOTES (Ehr. 1831) Stein '59.
(Ehrenberg '31, '38; Stein '59; Cl. & Lach. '58; Quennerstedt '65,
'67, '69; Bütschli '88; Kent '81; Gourret & Roeser '88; Möbius '88.)
Small to medium-sized forms. Rigid in form, colorless, or green by
chlorophyl. They are quite flat on the ventral surface but decidedly
arched dorsally, and the contour is usually oval. The anterior end is
broadly rounded to truncate; the posterior end is similarly rounded,
or may be somewhat pointed. The mouth is placed centrally or near
the left margin, and from it the right edge of the peristome forms a
curved line to the left, which bends forward, thus making the greater
part of the left edge the peristomial area. In front the peristome
bends sharply to the right and extends as far as the right end of the
adoral zone. Upon the frontal and median ventral surface are 9 to 10
great cirri (_Bauchwimpern_ of Stein). Posteriorly five great anal
cirri stretch out beyond the posterior body margin. In addition to
these there are two smaller marginal cirri upon the left body edge,
and two similar ones on the hinder part of the body. The dorsal
surface is rarely smooth, but usually is marked by longitudinal
ridges, and rows of dorsal bristles have been described. The single
contractile vacuole lies on the right side in the region of the
anal cirri, sometimes just above them, sometimes below. The anus is
posterior and on the right side. The characteristic macronucleus is
long and band-form, its main portion being usually on the left side
with an anterior and a posterior arm toward the right. Movement is
rapid swimming, which, however, is frequently broken by creeping
periods, during which the animals appear to be examining the foreign
body on which they creep.
Fresh and salt water.
Euplotes charon Ehr. Fig. 52.
Synonyms: _Trichoda charon_ Müller; _Ploesconia charon_; _P.
affinis_, _subrotunda_, _radiosa_, _longiremis_, Dujardin '41.
The body is oval, small, and somewhat variable in length. The
carapace is strongly marked upon the dorsal side by deep longitudinal
grooves, 6 to 8 in number; the grooves may be absent, however. The
adoral zone extends to the posterior third of the body, the mouth
and oesophagus are directed anteriorly. There are 10 ventral cirri,
7 of which are on or near the frontal border and 3 near the right
edge. There are 5 posterior cirri and 4 anal cirri, of much smaller
size. The cirri may or may not be fimbriated, the latter condition
indicating the approaching disintegration of the body and is
abnormal. The macronucleus is long and band-formed or horseshoe
shape. The contractile vacuole lies on the right side dorsal to the
posterior cirri.
Fresh and salt water. Length 45µ; diameter 25µ.
[Illustration: Fig. 52.--_Euplotes charon_, dorsal and ventral
aspects.]
Euplotes harpa Stein. Fig. 53.
The body is elongate, oval, somewhat widened anteriorly, and has
rounded ends. The frontal margin is three-toothed. Ten ventral cirri.
Dorsal surface provided with 8 longitudinal markings. The peristome
is long and broad, with considerable variation. The adoral zone
consists of powerful membranelles arranged in a continuous curve
from the mouth to the extreme right frontal margin. Seven of the 10
ventral cirri are situated at the anterior extremity; the remainder
are arranged in a triangle on the right edge. The anal cirri, 5 in
number, are long and stiff; the marginal cirri smaller and finer. The
nucleus and contractile vacuole are similar to those of the preceding
species.
Length 95µ; width 54µ.
[Illustration: Fig. 53.--_Euplotes harpa_.]
Genus DIOPHRYS Dujardin '41.
(Bütschli '88.)
Medium size, colorless to yellow, rigid in form. The body contour
is oval, the anterior end being rounded or slightly reduced, the
posterior end usually cut in on the right side. The peristome is
broad but less extensive than in _Euplotes_, and may extend beyond
the middle of the body. Its right edge is convex toward the right
side, extends forward and does not turn again to the right. The
anterior ventral surface has 7 to 8 scattered cirri and just behind
the mouth is a transverse row of large anal cirri. In the sharp
in-cut of the posterior end are three great angular cirri. Two
lateral cirri are placed on the left of the median line between
the mouth and the anal cirri, and usually in a slight hollow. The
contractile vacuole is on the right side in the vicinity of the
anal cirri. The macronucleus is in two parts, each band-form, one
anterior, the other posterior in position. Movement is rapid and
steady. Salt water.
Diophrys (Styloplotes) appendiculatus Stein '59. Fig. 54.
Synonyms: _Styloplotes appendiculatus_ Stein '59; Kent '81;
Quennerstedt '67, etc.
The general form resembles _Euplotes_. Its outline is oval and
regular except at the posterior end on the right side, where there is
a considerable indentation. The frontal margin is characterized by a
row of powerful membranelles, which become smaller at the peristome
and at the mouth they are of characteristically small size. The
ventral cirri are 7 in number. Five of them are in one row from the
anterior end down the right side nearly to the anal cirri; 1 is on
the frontal border between the first two; 1 lies just anterior to the
second anal cirrus from the right side. The 5 anal cirri are large
and powerful and extend some distance beyond the posterior end of the
body. In all specimens observed these cirri curve to the left. Dorsal
to the anal cirri and placed deep into the dorsal pit are 3 large,
sharply curved cirri, which in most cases are fimbriated, but when
the specimens are normal these are pointed and curve abruptly to the
right. Two smaller cirri lie to the left of the group of anal cirri.
The peristome is well-marked by the adoral zone, and upon its right
border there is a row of cilia, and a similar row of cilia runs along
the base of the oral membranelle. The macronucleus is double and
consists of two elongate cylindrical masses lying parallel with
one another. One of these is in the anterior region; the other is
posterior. The contractile vacuole lies dorsal to the anal cirri
and anterior to the three dorsal cirri. The movement and general
activities resemble those of _Euplotes_.
Length 50µ; diameter 25µ.
[Illustration: Fig. 54.--_Diophrys appendiculatus_.]
Genus URONYCHIA Stein '52.
(Stein '59, '67; Quennerstedt '67; Kent '81; Bütschli '88.)
Medium-sized colorless ciliates of usually constant body form. The
body is somewhat short and oval in outline. The anterior end is
broadly truncate, the posterior end rounded or slightly pointed. The
ventral and dorsal surfaces are considerably arched and the latter
usually has a number of rows of longitudinal stripes. The open
peristome is broad and reaches back to the middle of the ventral
surface and beyond. According to Stein, the two edges can approach
each other, thus opening and closing the peristomial area. Its right
edge forms a greater angle with the front edge than in the genus
_Euplotes_, and the left edge forms a greater angle with the front
edge than in that genus. The left edge also appears to cover over the
adoral zone slightly. There are no ventral cirri in front, but on the
posterior ventral surface are 7 great springing cirri. Five of these
are inserted on the right aide in a deep in-sinking, and the other 2
in a similar depression on the left ventral surface. Above the 5
right-side cirri, _i.e._, dorsal to them, but in the same depression,
are 3 angular cirri. A few edge cirri are found to the left of them
and another to the right of the 5 cirri. The contractile vacuole is
on the left side between the main groups of cirri. The macronucleus
is band-form or spherical, and is situated in the middle region of
the body. Movement consists in forward swimming with sudden springs.
Salt water.
Uronychia setigera, n. sp. Fig. 55.
This species is very common in the Woods Hole waters. It is small,
colorless, and very active. The most characteristic feature is
the posterior end with its relatively enormous cirri, which are
apparently large enough for an animal four times its size. The form
is ovoid, widened posteriorly.
The ventral surface is flat and has two excavations in the posterior
end. The right hollow is larger and contains 5 great cirri of unequal
size, the extreme right one being the largest. The left hollow
contains 2 cirri, also of dissimilar size. Dorsal to the 5 right
cirri are 3 sickle-formed cirri, which are usually fimbriated. These
are pointed and curve regularly to the left. The peristome is wide
and open, and a small pocket-like hollow on its left border indicates
the region of the mouth. The adoral zone runs into this pocket
and the mouth is located in its lower right-hand corner. In _U.
transfuga_ the right border is generally described as having a
membrane of extreme delicacy. I was unable to see such a membrane in
this form, but in its place there are 2 flagella-like cirri extending
from the margin of the mouth-opening into the peristome, and these
vibrate slowly. I do not believe these could be the moving edge of an
undulating membrane, for they are quite distinct. The macronucleus is
spherical instead of band-form, and a single micronucleus is closely
attached. This is unlike the European species _U. transfuga_, in
which the nucleus is elongate. The contractile vacuole lies between
the two sets of posterior cirri. There are no marginal folds like
those of the European species.
Length 40µ; width 25µ. Common.
[Illustration: Fig. 55.--_Uronychia setigera_.]
Genus ASPIDISCA Ehr. 1830.
(Perty '52; Cl & Lach. '58; Stein '59; Quennerstedt '65, '67, '69;
Mereschowsky '79; Kent '81; Bütschli '88.)
Small, colorless, and rigid forms, with nearly circular to oval
contour. The left side is usually straight, or at least but slightly
convex. The right side is much more convex, and the right margin is
considerably thickened. The ventral side is flat, the dorsal surface
convex, with from one to several longitudinal ridges which run more
or less parallel with the right edge. The peristome is limited to the
left edge, where it forms a small depression which may or may not
reach the anterior border, but which in no case runs around the
anterior margin. The left peristome margin in some cases grows
over the peristome depression toward the right, thus making a sort
of cover for the peristome. In the posterior region is a deep
depression, from which 5 to 12 cirri take their origin. Seven or 8
cirri are placed in the anterior half of the ventral surface and
are arranged more or less in rows. The anus is on the right side in
the region of the anal cirri (Stein). The contractile vacuole is
generally on the right side and similarly located. The macronucleus
is a horseshoe-shaped body. Movement rapid, somewhat in circles, and
rather uniform.
Fresh and salt water.
Aspidisca hexeris Quennerstedt '67. Fig. 56.
The carapace is elliptical, about 1-1/2 times as long as broad,
rounded at the extremities. The left border of the carapace bears a
spur-like projection. The ventral cirri are short and thick, and are
very characteristic of the species. When moving slowly they look much
like nicely-pointed paint brushes, but when the animal is compressed
they quickly become fibrillated, and then look like extremely old and
worn brushes. These cirri are placed in depressions in the ventral
surface and each one appears to come from a specific shoulder. At the
posterior end an oblique hollow bears 6 unequal cirri placed side
by side. The extreme right cirrus is the largest, and they become
progressively smaller to the opposite end. Dorsal to these lies the
contractile vacuole. The peristome is in the posterior half of the
body and an undulating membrane extends from it into the oesophagus.
The dorsal surface is longitudinally striated by 5 or 6 lines, which
are usually curved. The nucleus is horseshoe-shaped and lies in the
posterior half of the body. Length 68µ; diameter 48µ.
[Illustration: Fig. 56.--_Aspidisca hexeris_.]
This form was incorrectly mentioned as _Mesodinium_ sp. by Peck '95:
In the figure given by Quennerstedt there are only 7 ventral cirri.
In the Woods Hole form there are 8, 7 of which are anterior, 6 of
them about one central one. The eighth cirrus is by itself, near the
base of the largest posterior cirrus. These cirri, in spite of their
size, are easily overlooked and more easily confused, but by using
methylene blue they can be seen and counted.
Aspidisca polystyla Stein. Fig. 57.
This species is similar to _A. hexeris_, but is smaller, very
transparent, and without the spur-like process on the left edge of
the carapace. The chief difference, however, lies in the number of
anal cirri. These are 10 in number and they are arranged obliquely as
in the preceding species, with the largest one on the right and the
smallest on the left. The ventral cirri are 8 in number, and are
arranged in two rows, one of which, the right, has 4 cirri closely
arranged, the other having 3 cirri close together and one at some
distance, near the largest anal cirrus. The peristome, contractile
vacuole, and nucleus are similar to the preceding. Length 36µ; width
22µ.
[Illustration: Fig. 57.--_Aspidisca polystyla_.]
Stein assigns only 7 ventral cirri to this species, but he also
describes 2 very fine bristle like cilia (p. 125) and pictures them
in figs. 18, 19, 20, and 21 of his Taf. III in the same relative
position as my eighth cirrus. I am positive that cilia do not occur
on the ventral face of this form, and that the characteristic cirri
are the sole locomotor organs.