In general the form is oval and either regular in outline or irregular through the presence of many pseudopodia. One flagellum usually quite large and distinct. Differentiation of ectoplasm and endoplasm distinct or wanting. One to several contractile vacuoles. The pseudopodia are occasionally withdrawn, and the flagellum is the sole means of locomotion. In some cases the flagellum turns into a pseudopodium, and, conversely, the pseudopodium at one end may become a flagellum (see below). In some rare cases the ectoplasm secretes a gelatinous mantle. Reproduction not observed.
Fresh and salt water.
Mastigamœba simplex, n. sp. Fig. 7.
A very small form, first seen in the flagellated stage, aroused my interest by reason of the fact that its flagellum lost its regular outline and became amœboid, turning to a pseudopodium, while at the same time other pseudopodia were protruded from different parts of the periphery. In this condition ectoplasm and endoplasm could be made out with the clearest definition. After the pseudopodia were well formed, the body became flat and closely attached to the glass slide. In a short time one of the pseudopodia became longer than the rest; the body became more swollen; the pseudopodia were gradually drawn in, with the exception of the more elongate one; this became active in movement and finer in diameter, until ultimately it formed a single flagellum at the anterior of a small monadiform flagellate. The process was repeated two or three times under my observation, so that I am convinced that it was not a developmental form of some rhizopod. Several of them were seen at different times during the summer, and they were always of the same size and form in the flagellated or amœboid condition. I did not make out their reproduction, and I shall not be satisfied that this is a good species until their life history is known.
In decaying algæ. Length 10µ.
(Kent '81.)
Small forms inclosed in cup or "house" of ovoid or goblet shape, colorless and probably gelatinous (chitin?) in texture, and borne upon a stalk. The monad does not completely fill the test. Contractile vacuole single, posterior.
Codonœca gracilis, n. sp. Fig. 8.
The cup is urn-shaped with a well-defined neck or collar borne upon a shoulder-like end of the body. It is hyaline, colorless, and carried upon a stalk equal in length to the cup or shorter than this. The animal does not fill the cup, nor is it attached by a filament to the latter. There is a single flagellum. The nucleus is minute and lateral in position; the contractile vacuole is in the posterior end of the body. Total length of cup and stalk 21µ; of cup alone 12µ. This minute form looked so much like a choanoflagellate that I supposed it to be one until I discovered an empty case (Fig. 8).
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 amœboid, 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.
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.
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.
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.
The body is naked, usually amœboid 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.
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.
| Bodo caudatus |
Fig. 14.—Bodo caudatus.
ENLARGE |
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.
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 œsophageal 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.
Flagellates with two flagella, of which one is directed forwards and is concerned with the locomotion of the animal, while the other is directed backwards and drags after the animal when in motion. Body slightly compressed dorso-ventrally (fig. 17, section). An oral furrow is present on the ventral side and the two flagella originate in it (fig. 17, at left). The vacuole is on the left side. Food vacuoles are present in the posterior part. The nucleus is central. Movement creeping.
Fresh and salt water.
Anisonema vitrea (Duj.) Fig. 17.
Synonyms: Tropidoscyphus octocostatus Stein '83; Sphenomonas Kent '81; Plœotia vitrea Senn 1900.
With the characteristics of the genus. It differs from freshwater forms in having eight furrowed surfaces running somewhat spirally from the posterior to the oral end. Length 50µ; width 23µ. This attractive flagellate was quite common in decaying algæ at Woods Hole; its shaking movement, its peculiar furrowed surfaces, and, above all, its perfectly transparent, vitreous appearance, were well described by Dujardin. Stein's Tropidoscyphus octocostatus is a fresh-water form which may possibly be a distinct species, especially as it is described with both flagella directed forwards.
An aberrant flagellate bearing a single flagellum and a silicious skeleton resembling those of the Radiolaria. The skeleton consists of two rings of different diameter parallel with one another and connected by silicious bars. From the wider ring half a dozen bars radiate outwards and a similar number of short thorn-like bars point inwards obliquely. The color is yellow, and except for the flagellum the form might easily be mistaken for a Radiolarian, as has been the case repeatedly.
Distephanus speculum Stöhr.
Dictyocha speculum Stöhr; Dictyocha Auc.
With the characters of the genus.
A single specimen only of this very interesting form was seen at Woods Hole. It occurred in a collection of tow made near the end of the wharf during the evening.
| Key to families of Dinoflagellidia. | ||
| 1. | No crossfurrow; two free flagella | Family Prorocentridæ |
| 2. | One or more cross-furrows | 3 |
| 3. | Cross-furrow nearly central (cf. Oxytoxum) | Family Peridinidæ |
| Cross-furrow close to anterior end | Family Dinophysidæ | |
| Several cross-furrows and flagella |
Family Polydinidæ (One genus, Polykrikos.) |
|
| Key to marine genera of Prorocentridæ. | ||
| Diagnostic characters: The transverse furrow is absent and the two flagella arise from the anterior end of the body. The shell may be bivalved. | ||
| 1. | No tooth-like process dorsal to the flagellum | Genus *Exuviælla |
| 2. | With tooth-like process dorsal to the flagellum | Genus Prorocentrum |
| * Presence at Woods Hole indicated by asterisk. | ||
| Key to marine genera of Peridinidæ. | ||
| Diagnostic characters: The cross-furrow is nearly central (see, however, Oxytoxum); the body may or may not have a shell; the shell may or may not be composed of distinct plates; the plates are distinguished as equatorial (i.e., bordering the cross-furrow), apical, and antapical, while still another, the "rhombic plate", may be present, extending from the cross-furrow to the apex. | ||
| 1. | Without distinct shell | Genus *Gymnodinium |
| With a distinct shell | 2 | |
| 2. | Shell not composed of definite plates | 3 |
| Shell composed of definite plates | 4. | |
| 3. | Cross-furrow replaced by thin-skinned band | Genus Ptychodiscus |
| Cross-furrow well defined; reticulate markings raised on shell-surface | Genus Protoceratium | |
| Cross-furrow well defined; no markings | Genus *Glenodinium | |
| 4. | Two parts of shell equal or nearly equal | 5 |
| Two parts of shell very unequal | 11 | |
| 5. | With transverse flagellum in a distinct furrow | 6 |
| Transverse flagellum not in a furrow | 10 | |
| 6. | With horns, or with wing-like processes | 7 |
| Without processes of any kind kind | 9 | |
| 7. | Processes small, wing-like, around flagellum-fissure | Genus Diplopsalis |
| Processes horn-like | 8 | |
| 8. | Anterior part with 7 equatorial and 1 rhombic plates | Genus *Peridinium |
| Anterior part with 5 equatorial and no rhombic plates | Genus Gonyaulax | |
| Anterior part with 3 equatorial and no rhombic plates | Genus *Ceratium | |
| 9. | Anterior part with 14 equatorial and 1 rhombic plates | Genus Pyrophacus |
| Anterior part with 7 equatorial plates | Genus Goniodoma | |
| Anterior part with 4 equatorial plates | Genus Amphidoma | |
| 10. | Apical extremity drawn out into a tube | Genus Podolampas |
| pical extremity not drawn out into a tube | Genus Blepharocysta | |
| 11. | Cross-furrow deep, with great ledge-like walls | Genus Ceratocorys |
| Cross-furrow wide, no ledge-like walls | Genus Oxytoxum | |
| * Presence at Woods Hole indicated by asterisk. | ||
| Key to marine genera of Dinophysidæ. | ||
| Diagnostic characters: The cross-furrow is above the center of the body, and its edges, as well as the left edge of the longitudinal furrow, are usually produced into characteristic ledges; those of the cross-furrow usually form great funnel-like anterior processes, while those of the longitudinal furrow usually form great, lateral, wing-like processes ornamented by ribs and other markings. | ||
| 1. | Without shell; longitudinal furrow may open & close | Genus *Amphidinium |
| 2. | With shell; longitudinal furrow unchangeable | 3 |
| 3. | With distinct apical funnel | 4 |
| No apical funnel | Genus Phalacroma | |
| 4. | With great wing-like ledge | 5 |
| Ledges very small; body long, needle-like | Genus Amphisolenia | |
| 5. | Ledge of longitudinal furrow extends to posterior end | 6 |
|
Ledge of longitudinal furrow does not extend to posterior
end (Recorded by Peck ('93-'95) as very abundant at Woods Hole and in Buzzards Bay.) |
Genus Dinophysis | |
| 6. | Ledge is continued dorsally to the cross-furrow | Genus Ornithocercus |
| Ledge is not continued dorsally | 7 | |
| 7. | With deep dorsal cavity; secondary funnel not notched | Genus Citharistes |
| No dorsal cavity; secondary funnel deeply notched | Genus Histioneis | |
| * Presence at Woods Hole indicated by asterisk. | ||
The form varies from globular to ovoid, with occasionally a sharp posterior end. Shells are usually somewhat compressed, and consist of two valves, which frequently slide one over the other in such a manner as to show the structure with great clearness. The right shell may have a distinct indentation in the anterior edge. There are two lateral, discoid, brown chromatophores, each of which possesses a central amylum granule. The nucleus is posterior. Salt water.
Exuviælla lima Ehr. Fig. 18.
Synonyms Pyxidicula Ehr.; Cryptomonas Ehr.; Prorocentrum lima Kent; Amphidinium Pouchet.
The shell is ovate, rounded and swollen posteriorly. The anterior border of both shells is slightly indented. The shell is quite thick. The animal moves through the water very slowly. Dark brown in color. Length 48µ; width 44µ.
| Exuviaella lima |
Fig. 18.— Exuviælla lima. ENLARGE |
Exuviælla 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.
| Exuviaella marina |
Fig. 19.— Exuviælla marina. ENLARGE |
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. sphærica, 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 68µ; width 55µ. Common.
| Gymnodinium gracile, var. sphaerica |
Fig. 20.— Gymnodinium gracile, var. sphærica. ENLARGE |
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 40µ; breadth 32µ; width 18µ.
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.