Marine Protozoa from Woods Hole | Page 3

Schneider. Fig. 3.
With the characters of the genus. A form which I have taken to be a
young stage of this interesting rhizopod is described as follows:
A minute, almost quiescent, form which changes its contour very
slowly. The membrane is cap-like and extends over the dome-shaped
body, fitting the latter closely. The endoplasm is granular and contains
foreign food-bodies. Nucleus single, spherical, and centrally located.
Pseudopodia short and finger-form, emerging from the edge of the
mantle-opening and swaying slowly from side to side or quiescent. The
most characteristic feature is the presence of a broad, creeping sole,
membranous in nature and hyaline in appearance. This membrane is the
only evidence of ectoplasm, and it frequently shows folds and wrinkles,
while its contour slowly changes with movements of body. The
pseudopodia emerge from the body between this membrane and the
shell margin. Contractile vacuole absent. Length 42µ, width 35µ. In
decomposing seaweeds, etc.
Only one specimen of this interesting form was seen, and I hesitate
somewhat in placing it on such a meager basis. It is so peculiar,
however, that attention should be called to it in the hope of getting
further light upon its structure and mode of life. Its membranous disk
recalls the genus Plakopus; its mononucleate condition, its
membranous disk, and the short, sometimes branched, pseudopodia
make it difficult to identify with any phase in the life-history of
Trichosphærium. I shall leave it here provisionally, with the hope that it
may be found more abundantly another time.
[Illustration: Fig. 3.--Trichosphærium sieboldi]
Genus GROMIA Dujardin '35.
(Dujardin 1835; M. Schultze '62; F. E. Schultze '74; Leidy '77; Bütschli
'83; Gruber '84.)

The form is ovoid or globular, and the body is covered by a tightly
fitting, plastic, chitin shell, which, in turn, is covered by a fine layer of
protoplasm. The flexibility of the shell makes the form variable as in
the amoeboid types. The thickness of the shell is quite variable. The
pseudopodial opening is single and terminal. The pseudopodia are very
fine, reticulate, granular, and sharply pointed, and form a loose network
outside of the shell opening. Nucleus single or multiple. Contractile
vacuole is usually absent. Fresh and salt water.
Gromia lagenoides Gruber '84. Fig. 4.
This species is not uncommon about Woods Hole, where it is found
upon the branches of various types of algæ. The body is pyriform, with
the shell opening at the larger end. The chitinous shell is hyaline and
plastic to a slight extent, so that the body is capable of some change in
shape. The shell is thin and turned inwards at the mouth-opening,
forming a tube (seen in optical section in fig. 4) through which the
protoplasm passes to the outside. The walls of this tube are thicker than
the rest of the shell, and in optical section the effect is that of two
hyaline bars extending into the body protoplasm. A thin layer of
protoplasm surrounds the shell and fine, branching, pseudopodia are
given off in every direction. The protoplasm becomes massed outside
of the mouth-opening and from here a dense network of pseudopodia
forms a trap for diatoms and smaller Protozoa. The nucleus is spherical
and contains one or two large karyosomes. The protoplasm is densely
and evenly granular, without regional differentiation. I have never
observed an external layer of foreign particles, such as Gruber
described in the original species.
Length of shell 245µ; largest diameter 125µ.
[Illustration: Fig. 4.--Gromia lagenoides.]
Genus TRUNCATULINA D'Orbigny.
A group of extremely variable foraminifera in which the shell is
rotaline; i. e., involute on the lower side and revolute on the upper
(Brady). The shell is calcareous and coarsely porous in older forms.

The characters are very inconstant, and Brady gives up the attempt to
distinguish the group by precise and constant characters.
Truncatulina lobatula Walker & Jacob.
Synonyms: See Brady '84 for a long list.
"It is impossible to define by any precise characters the morphological
range of the present species. Its variations are infinite." (Brady, p. 660.)
This very common form, which occurs in all latitudes, was found
frequently among the algæ at Woods Hole. Its characters are so
difficult to define that for the present I shall limit my record to this
brief notice. Size of shell 230µ by 270µ.
Genus ACTINOPHRYS Ehr.
The body is spherical and differentiated into granular endoplasm and
vacuolated ectoplasm, but the zones are not definitely separated. There
is one central nucleus and usually one contractile vacuole. The
pseudopodia have axial filaments that can be traced to the periphery of
the nucleus. Fresh and salt water.
Actinophrys sol Ehr., variety. Fig. 5.
Synonyms: See Schaudinn '95.
The diameter is about 50µ; the vacuolated ectoplasm passes gradually
into the granular endoplasm. This is the characterization given _A. sol_
by Schaudinn, and it applies perfectly to