(Kent '81; Bütschli '86; Klebs '97; Senn 1900.)
The body is small, globular or oval and either free-swimming or
fastened by one of the two flagella. The body is sometimes a little
amoeboid, with short pseudopodial processes. In addition to the main
flagellum, there are usually one or two small flagella at the basis
of the larger one. The nucleus is usually anterior, and one or two
contractile vacuoles are present.
Monas sp. Fig. 9.
An extremely small form (3µ) attached by a thread of
protoplasm--perhaps a flagellum, to algæ. The body is ovoid and
the main flagellum is about four times the length of the body. The
contractile vacuole is posterior. Only one specimen was seen and
upon this I shall not attempt to name the species.
[Illustration: Fig. 9.--_Monas_ sp.]
Genus MONOSIGA Kent '81.
(Bütschli '86; Francé '97; Senn 1900.)
Small colorless forms of Choanoflagellida, always naked and solitary.
The posterior end is attached directly to the substratum, or
there is a short stalk not exceeding the body in length. Kent '81
distinguished nine species, but Bütschli questioned the accuracy
of many of these, and in this he was followed by Francé '97, who
recognized three species--_Monosiga ovata_, _M. fusiformis_, and _M.
augustata_. Fresh and salt water.
Monosiga ovata S. Kent '81. Fig. 10.
Synonyms: _M. brevipes_ S. K.; _M. consociata_ S. K.; _M. limnobia_
Stokes.
The individuals are unstalked or provided with a very short stalk
less than the body in length. The form is spherical or ovate,
broadest at the base and tapering to the extremity. The collar is
somewhat variable in size. In the Woods Hole forms it was about
the length of the body. Oil particles present. Contractile vacuole
posterior, nucleus anterior.
Fresh and salt water. Length of body without the collar 5µ.
[Illustration: Fig.10.--_Monosiga ovata_.]
Monosiga fusiformis S. K. Fig. 11.
Synonyms: _M. steinii_ S. K.; _M. longicollis_ S. K.
The individuals are unstalked, minute, and of a general flask-shape.
The body is swollen centrally and tapers slightly at each end. There
is no stalk, the body being fixed by the attenuate posterior end.
There are two contractile vacuoles and one nucleus, which is situated
a little above the body center. Fresh and salt water. Length without
collar 9µ; length of collar 3µ.
[Illustration: Fig. 11.--_M. fusiformis_.]
Genus CODONOSIGA (Jas. Clark '67).
(Bütschli '78; Kent '81; Francé '97; Senn 1900.)
This genus, as modified by Francé, is distinguished from the
preceding by the possession of an unbranched stalk much longer than
the body length. The body is naked and of various shapes, and the
individuals are solitary or colonial upon a single stalk. Kent '81
enumerates no less than 10 species, which were cut down by Bütschli
to 1. Francé admits 4--_C. botrytis_ Jas. Clark; _C. grossularia_;
_C. pyriformis_, and _C. furcata_, all S. Kent--but regards the
second and third as merely form varieties of the first.
Codonosiga botrytis (Ehr. sp.) Jas. Clark '67. Fig. 12.
Francé gives the following synonyms: _Epistylia botrytis_ Ehr.;
_E. digitalis_ Stein, _Zoothamnium parasitica_ Stein; _Anthophysa
solitaria_ Fresenius; _Codonosiga pulcherrima_ Jas. Clark; _Monosiga
gracilis_ S. Kent; _M. globulosa_ S. Kent; _Codonosiga pyriformis_
Kent; _C. grossularia_ Kent; (Francé).
The individuals are small and provided with a long unbranched, or
terminal, simply split stalk. The individuals are single or colonial.
The Woods Hole form measured 22µ over all; the body was 5µ, the
collar 3µ, and the stalk 14µ. No colonies were seen, and only a few
individuals upon red algæ.
[Illustration: Fig. 12.--_Codonosiga botrytis_.]
Genus BODO (Ehr.) Stein.
(Stein '59, Bütschli '83; Klebs '92; Senn 1900.)
The body is naked, usually amoeboid in its changes, and provided with
two flagella, one of which is usually trailed along under and behind
the animal. The anterior end is usually pointed, with the flagella
arising from a minute depression; the posterior end is rounded.
Specific characters very difficult to analyze. Fresh and salt water.
Bodo globosus Stein. Fig. 13.
The body during movement is globular or ovoid, without any anterior
process. The trailing flagellum is invariably much longer than the
vibratory one. The contractile vacuole lies in the anterior half of
the body. Solid food particles are taken in near base of flagella.
Length of body 9 to 12µ; diameter 8 to 11µ. Common.
[Illustration: Fig. 13.--_Bodo globosus_.]
Bodo caudatus (Duj.) Stein. Fig. 14.
Synonyms: _Amphimonas caudatus_ Duj.; _Diptomastix caudata_ Kent.
The body is variable in shape, but usually flattened and pointed
posteriorly. An anterior process is almost always present, and
below this the flagella are inserted in a minute depression. The
contractile vacuole is close to the base of the flagella. The
flagella are about the same size, the anterior one usually somewhat
longer. Common. Length 12 to 18µ.
This species was seen by Peck '95 and described as a small
flagellate.
[Illustration: Fig. 14.--_Bodo caudatus_.]
Genus OXYRRHIS Duj.
(Kent '81; Bütschli '86; Klebs '92; Senn 1900.)
Medium-sized forms, somewhat oval in shape, with a rounded posterior
end. The anterior end is continued dorsally in a somewhat attenuate
pointed process. At the base of this process is a large cavity or
funnel, on the dorsal wall of which, or on a projection from this
wall, are two equal-size flagella. When at rest, the flagella are
directed backwards. The nucleus is central. In moving, the posterior
end is invariably in advance. This genus is exceptional among
Mastigophora in that division is transverse instead of longitudinal.
Oxyrrhis marina Duj. Fig. 15.
With the characters of the genus. Contractile vacuole not seen.
Length 28 to 40µ.
[Illustration: Fig. 15.--_Oxyrrhis marina_.]
Genus ASTASIA Ehr.
Flagellates with one flagellum, a spindle-form body and a high
degree of plasticity, the contour constantly changing. A distinct,
usually striped cuticle is invariably present. "Eye-spots" are
absent. Fresh and salt water.
Astasia contorta Duj. Fig. 16.
_Astasia inflata_ Duj. '41.
The body is colorless, transparent, and flexible. It is largest in
the center, thence tapering at the two extremities. The surface of
the cuticle is obliquely striated, giving to the animal a distinctly
twisted appearance. The contractile vacuole is in the anterior
neck-like portion of the body. The flagellum is inserted in a
distinct oesophageal tube, into which the contractile vacuole
empties. This tube is continued into a deeper pharyngeal apparatus of
unknown function.
Common in decaying algæ. Length 60µ; greatest diameter 30µ.
[Illustration: Fig. 16.--Two aspects of _Astasia contorta_.]