Marine Protozoa from Woods Hole | Page 8

is slightly indented. The shell is quite thick. The animal moves through the water very slowly. Dark brown in color. Length 48��; width 44��.
[Illustration: Fig. 18.--Exuvi?lla lima.]
Exuviaella marina Cienkowsky. Fig. 19.
A smaller form than the preceding, more elliptical in outline, with a thinner shell and with large granules throughout the endoplasm. The nucleus is spherical and subcentral in position and possesses a distinct central granule. This may be a small variety of E. lima.
[Illustration: Fig. 19.--Exuvi?lla marina.]
Genus GYMNODINIUM Stein '78.
(Bergh '81; Kent '81; Pouchet '83, '85; Entz '84; Sch��tt '95.)
The general structure of these forms is similar to that of Glenodinium; the most striking and positive difference is the absence of a shell. The animals are, as a rule, spherical, yet they may be pointed at the two ends or at one of them. They are also frequently flattened dorso-ventrally. The transverse furrow may be either circular and straight around the body or may describe a spiral course, passing even twice around the body. The flagella arise near cross-furrow or, in some cases, in longitudinal furrow. Chromatophores may or may not be present and food-taking is holozoic, in many cases at least. In some cases ectoplasm and endoplasm can be distinguished. Fresh and salt water.
Gymnodinium gracile Bergh '82, var. sph?rica, n. Fig. 20.
The body is divided by the transverse furrow into a shorter anterior and a longer posterior part. The longitudinal furrow is broader at the posterior extremity than at the cross-furrow. The structural feature upon which this new variety is made is the unvarying plumpness of the body, making it almost spherical, except for a slight flattening dorso-ventrally. The nucleus is large and ellipsoidal, with characteristic longitudinal markings of chromatin. The endoplasm is evenly granular, with a number of large ingested food bodies. The color is brown, not rose-red as in Bergh's species, nor is the Woods Hole form as large as the latter. Length of body 68��; width 55��. Common.
[Illustration: Fig. 20.--Gymnodinium gracile, var. sph?rica.]
Genus GLENODINIUM (Ehr.), Stein '83.
(Bergh '82; B��tschli '86; Pouchet '85; Daday '86.)
Small globular forms with two distinct furrows, one transverse around the body, the other longitudinal upon the face only. The shell is soft and structureless with a distinct aperture near the meeting point of the two furrows. The endoplasm usually, but not always, contains a bright red eye-spot.
Fresh and salt water.
Glenodinium compressa, n. sp. Fig. 21, a, b, c.
This species resembles G. acuminata of Ehrenberg except that it is strongly compressed laterally. The longitudinal furrow extends nearly to the extremity of the animal. It begins as a narrow slit and widens as it progresses upon the left side; it also becomes much deeper on this side and at the bottom of the depression the longitudinal flagellum is inserted. The transverse furrow runs evenly around the body near the upper pole, giving to the shell almost the aspect of an Amphidinium. Brown chromatophores may or may not be arranged radially about a central amylum granule. One striking characteristic is the depth of the two furrows. The nucleus is elongate and somewhat curved; it lies against the posterior wall of the rather thick shell. Not uncommon.
Length 40��; breadth 32��; width 18��.
The posterior end of the animal is often somewhat pointed and this point frequently becomes attached, so that the animal whirls around upon it as upon a pivot.
[Illustration: Fig. 21 a, b, c.--Glenodinium compressa, n. sp.]
Glenodinium cinctum Ehr. Fig. 22.
The body is globular, smooth, and homogeneous. Brown chromatophores arranged radially, each in the form of a cone, the base of which rests against the shell while the points turn inward. A bright-red eye-spot may or may not be present; when present it is placed near the junction of the two furrows. The longitudinal furrow is small. Fresh water and salt.
Length and diameter the same, 21��.
This species was observed by Peck '93.
[Illustration: Fig. 22.--Glenodinium cinctum.]
Genus PERIDINIUM Ehr. '32, Stein '83.
(Clapar��de & Lachmann '58; Bergh '81; Pouchet '83; '85; Gourret '88; B��tschli '86.)
The form is globular, ovoid or elongate, the apex frequently drawn out into a long tube. The transverse and longitudinal furrows are quite distinct, the former having often a spiral course about the body. The two halves of the body are similar, the posterior being somewhat shorter; the anterior half has seven equatorial plates, an oral plate, two lateral apical plates, and one or two dorsal plates. The two antapical plates frequently have a tooth-like process. The bodies are colorless, green or brown.
Fresh and salt water.
Peridinium digitale Pouchet. Fig. 23.
Synonyms: Protoperidinium digitale Pouchet; Protoperidinium Bergh p. p.; P. divergens Peck.
The shell is covered with pits of large size. The posterior part is hemispherical and surmounted by a single horn or spine. The transverse furrow is very oblique, and its two extremities are united by a sigmoid longitudinal furrow. The anterior half bears two spines or