CHAP. VIII. OF THE ANIMALCULA INFUSORIA. (continued 3)

299. Vorticella Stellina.

V. orbicularis, disco moleculari, peripheria ciliata. Orbicular vorticella, with a molecular disc, and ciliated margin.

300. Vorticella Discina.

V. orbicularis, margine ciliato, subtus convexo-ansata. Plate XXVI. Fig. 8, 9, 10. Orbicular vorticella, the edge ciliated, with a kind of convex handle on the under-side.

301. Vorticella Scyphina.

V. craterformis, crystallina, medio spærula opaca. Bowl-shaped vorticella, crystalline, with an opake spherule in the middle.

302. Vorticella Albina.

V. cylindrica, postice acuminata. The fore-part cylindrical, the hinder-part tapering, and ending nearly in a point.

303. Vorticella Fritillina.

V. cylindrica vacua, apice truncata, ciliis prælongis. Empty cylindrical vorticella, the apex truncated.

304. Vorticella Truncatella.

V. cylindrica, differta, apice truncata, cyliis breviusculis. Cylindrical vorticella, stuffed or filled, the apex truncated, with very short cilia.

This is one of the larger kind of animalcula; the body is crystalline, and replete with black molecules; the skin is perfectly smooth and colourless, the hinder extremity rounded, and the anterior truncated; at this extremity there is a large opening thickly ciliated, which serves as a mouth.

305. Vorticella Limacina.

V. cylindrica, truncata, ciliis bigeminis. Plate XXVII. Fig. 60. Cylindrical truncated vorticella, with two pair of cilia.

306. Vorticella Fraxinina.

V. gregaria, cylindracea, oblique truncata, ciliis bigeminis, apice margine fissa. Gregarious cylindrical vorticella, obliquely truncated, with two pair of cilia, and a fissure or notch at the upper edge.

The greater part of the body is cylindrical; the hinder-part rather tapering, and filled with opake molecules; towards the upper end it is transparent; within the edge, at the top are two small tubercles, from each side of which proceed a pair of small hairs.

307. Vorticella Crategaria.

V. composita, floribus muticis globosis; tentaculis binis, stirpe ramosa, Plate XXII. Fig. 40. Compound, with globous naked florets, two tentacules, and a branched stem. For an ample description of this animalculum, see page 400.

308. Vorticella Hamata.

V. bursæformis, margine aperturæ aculeis rigidis. Plate XXVII. Fig. 40. Purse-formed; the edge of its aperture or mouth set with rigid points.

It is not ciliated, nor have any hairs been discovered upon it; the body is granulated, the fore-part broad and truncated, the hinder-part obtuse, and capable of being contracted or extended. a, the rigid points.

309. Vorticella Crateriformis.

V. subquadrata, ciliorum fasciculis etiam postice. Plate XXVII. Fig. 40, 41. Approaching somewhat to a square figure, with fascicles of cilia even at the hinder-part.

A lively animalculum, pellucid, round, longer than it is broad, with convex sides; the head is situated at the large end, the skin smooth, and some traces of intestines may be discovered with difficulty. There is a considerable opening surrounded with hair at the larger end, and the filaments composing it are in continual motion. Two of them are sometimes seen joined together, as at Fig. 41, and full of small spherules; in this state they draw each other alternately different ways, the surface is smooth and the hairs invisible. e, moveable cilia.

310. Vorticella Canaliculata.

V. dilatata, pellucida, latere inciso. Dilated, pellucid, with an incision in the side.

To the naked eye it appears as so many white points adhering to the sides of the glass; when magnified, the anterior part is narrower than the hind one; in the side a kind of incision may be perceived, and the hind-part is a little notched towards the middle; it is furnished with a rotatory organ, with which it excites a continual whirling motion in the water.

311. Vorticella Versatilis.

V. elongata spiculiformis, mox urceolaris. Long spear-formed vorticella, but which often changes its shape into a pitcher-like form.

A pellucid, gelatinous animalculum, of a greenish colour, furnished with small radii, particularly about the circumference, which gives it the appearance of a minute water hedge-hog.

312. Vorticella Ampulla.

V. folliculo ampulaceo, pellucido, capite bilobo. Plate XXVI. Fig. 4 and 5. This vorticella is contained in a pellucid bottle-shaped bag, the head divided into two lobes.

Little more need be said to enable the reader to know this animalculum, if he should meet with it, than to observe that the bag is nearly in the shape of the common water-bottle, and that the animalculum is sometimes to be observed at the bottom of it, sometimes nearly filling it.

313. Vorticella Folliculata.

V. oblonga, folliculo cylindraceo hyalino. Oblong vorticella, in a bright cylindrical bag.

This animalculum is gelatinous and cylindrical; when at its greatest extension, the base appears attenuated, and the apex truncated.

314. Vorticella Larva.

V. cylindrica, apertura lunata, spinis caudalibus binis. Cylindrical, the aperture somewhat in the shape of a crescent, two small thorny points projecting from the hinder-part.

The head, the trunk, and the tail, may be easily distinguished from each other. It is of a clay-colour, the aperture ciliated; with a globular projection at times appearing to proceed from it.

315. Vorticella Sacculata.

V. inverse conica, apertura lunata, trunco postice bidentato, cauda elongata biphylla. Plate XXVII. Fig. 42 and 43. This vorticella is in the shape of an inverted cone, with an aperture the figure of a crescent; the lower part of the trunk is notched, forming as it were two teeth; the tail biphyllous. Each of these parts is surrounded with a loose bright skin, the head is divided from the trunk by a deep incision. a a a, small points projecting from the head; b, the cilia; c and d d, the interior parts; Fig. 42, l, the little horn at the bottom of the trunk.

316. Vorticella Aurita.

V. cylindrico-ventrosa, apertura mutica, ciliis utrinque rotantibus cauda, articulata biphylla. Cylindrical and big-bellied, the aperture destitute of hairs, both sides of it are furnished with rotatory cilia, the tail biphyllous.

317. Vorticella Tremula.

V. inverse conica, apertura lobata spinulosa, cauda brevi unicuspi. Somewhat of a conical shape; the mouth being divided into two parts which are set with small spines, and a point projects from the tail.

It is a pellucid crystalline ventricose animalculum, within the body on one side, there is a large clay-coloured oval mass, and a pellucid oval substance adjacent to it; the tail is articulated and very short.

318. Vorticella Serita.

V. inverse conica, apertura spinosa integra, cauda brevi bicuspi. Somewhat of the shape of a cone, the aperture set with spines, the tail short and divided into two points.

The body is muscular, pellucid, folding variously; the fore-part truncated; round the margin of the aperture are rows of hairs, but it has also stiffer hairs or spines continually vibrating, with which it draws in both animate and inanimate substances. It has some resemblance to the larger vorticella rotatoria, but is easily distinguished from it by its horned spiny aperture, and simple rotatory organ.

319. Vorticella Lacinulata.

V. inverse conica, apertura lobata, setis binis caudalibus. Plate XXVII. Fig. 45. Shaped like an inverted cone, the aperture lobated, the tail small and furnished with two bristles, d.

The body is pellucid, cylindrical, and muscular; the apex about a third part down, drawn into a little neck; in the middle is a little lamina or triangular point; another of these is discovered when the aperture faces the observer, which makes it appear like a small flower. The hind-part, when in motion, is a little bent; it terminates in two minute bristles, which are seen sometimes united, at other times diverging. When the animalculum is swimming, its rotatory organ, a, may be seen; molecular intestines are visible; it moves with velocity in an oblique direction. It is found in pure water.

320. Vorticella Constricta.

V. elliptico-ventricosa, apertura integra, cauda annulata biphylla. Elliptical ventricose vorticella, the aperture or mouth undivided, the tail annulated and forked.

There are two kinds of this vorticella; viz. one of a pale yellow, the other of a white colour; the head, the tail, and the trunk, are fully distinguished; a substance in motion has been perceived, which has been supposed to be the heart; they move by fixing their tail to the glass upon the stage of the microscope, and extending their body as much as possible; they then fix the fore-part to the place where they intend to move, and draw the hinder-part to it, proceeding thus alternately. They sometimes turn round about upon one of the points of their tail, at other times they spring forwards with a jerk. When at rest they open their mouths very wide; the lips are ciliated, in some of them two black globules are discovered.

321. Vorticella Togata.

V. subquadrata, apertura integra, spinis caudalibus binis, plerumque unitis. Square vorticella, the aperture not divided, the tail consisting of two long spines, which are sometimes so united as to appear as one.

The body is convex, of a dark colour, and filled with molecules; the middle part is pellucid, the hinder-part rather broader than the fore-part; the latter is ciliated, and the tail formed of two very thin pellucid spines, which are somewhat curved and much longer than the body.

322. Vorticella Longiseta.

V. elongata, compressa, setis caudalibus binis longissimis. Long vorticella, flat, the tail formed of two very long bristles.

The fore-part sinuated, and set with minute cilia; the two bristles which constitute the tail are long, but one is longer than the other.

323. Vorticella Rotatoria.

V. cylindrica, pedicello collari, cauda longa quadracuspi. Plate XXVI. Fig. 1, 2, 3, 6, 7, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, and Plate XXVII. Fig. 46, 47, 48, and 49. Cylindrical vorticella, with a little foot projecting from the neck, a long tail furnished with four points.

Brachionus corpore conico subæquali. Hill Hist. Anim. Brachionus corpore conico toruloso. Ibid. Brachionus. Pallas Zooph. 50. Joblot Micros, part 2, p. 77, pl. 10, fig. 18; and p. 96, pl. 5, A B C D E K. Adams’s Microgr. Illustr. p. 148, pl. 40, fig. 255. Leeuwenhoeck Contin. Arc. Nat. p. 386, fig. 1, 2. Baker’s Micros. made easy, p. 91-93, pl. 8, fig. 6, 7, 8. Ibid. Empl. for the Micr. p. 267-294, pl. 11, fig. 1 to 13. Spallanz. Opusc. Phys. 2, p. 301, 315, pl. 4, fig. 3, 4, and 5. Rozier Journal Physique, 1775, p. 220.

This animalculum has long been known by the name of the wheel animal; in the description of which no person appears to have succeeded so well as Baker; and to him every writer has since referred for an ample account of this curious little being. What I shall now say on the subject will be chiefly extracted from the same source of information, with such alterations and additions as appear to be necessary to render his account more complete.

I shall begin with observing, that Müller’s wheel animal differs in some respects from that of Baker’s; first, with regard to the rotatory organs which are extended on the back like ears; secondly, the two little splendid substances within the body; and thirdly, the two black points near the top of the head, which are probably the creature’s eyes.

This little animal is found in rain water that has stood for some days in leaden gutters; in the hollows of lead on the tops of houses; or in the slime and sediment left in rain water; they are also sometimes to be met with in ditches and amongst duck-weed.

It has been called the wheel animal, because it is furnished with a pair of instruments, which in figure and motion resemble wheels. It appears only as a living creature when immersed in water; notwithstanding which, it may be kept for many months out of water, and in a state of perfect dryness, without losing the principle of life. When dry, it is of a globular form, about the size of a grain of sand, and without any apparent signs of life. If it be put into water, in the space of half an hour a languid motion begins, the globule turns itself about, lengthens itself by slow degrees, and becomes very lively; in a short time it protrudes its wheels, and swims about in search of food; or else, fixing itself by its tail, brings the food to it by its rotatory organs, which throw the whole circumjacent fluid into a violent commotion; when its hunger is satisfied, it generally becomes quiescent, and sometimes resumes its globular form.

If the water that is found standing in gutters of lead, or the sediment it has left behind, has any appearance of a red or a dark brown colour, little doubt need be entertained of its containing these animalcula. In the summer season, if a small quantity of this dust be put into water, and placed under a microscope, it seldom fails of discovering a great number of minute reddish globules, which are, in fact, the animals themselves. It will be best to view them first with the third or fourth magnifiers, and afterward apply those possessing greater powers.

The motions of this little creature somewhat resemble those of a caterpillar; like many of those insects, removing itself from place to place by first fixing the tail to some substance, then extending the whole body, fixing the head, and afterward drawing the tail to it; by these alternate actions it moves with some degree of swiftness.

This animal frequently changes its appearance, and assumes a very different form; for, the snout being drawn inwards, the fore-part becomes clubbed, and immediately dividing, exhibits to our view two circular instruments set with minute hairs, that move very briskly, sometimes in a rotatory, at other times in a kind of trembling or vibratory manner. An aperture or mouth is also perceived between the two semicircles; whilst in this state, the animal may often be perceived swimming about in pursuit of food.

The most distinguishing parts of this animalculum are, the head, the thorax, and the abdomen. It differs from any other creature hitherto described in the wonderful form and structure of its head; the sudden changes of which from one form to another are equally surprizing and singular; from being of a very taper form, it becomes almost instantaneously as broad as any part of its body, and protrudes an amazingly curious machinery formed to procure its food.

The circular bodies which project from the animal have much the resemblance of wheels, appearing to turn round with considerable velocity, by which means a very rapid current of water is brought from a great distance to its mouth. As these wheels are very transparent, the edges excepted, which are set with fibrillæ, as cogs to a wheel, it is difficult to determine how the rotatory motions are performed, or whether their figure be flat, concave, or conical; be this as it may, they are protruded from a couple of tubular cases, into which they can be again withdrawn, at the will and pleasure of the animal. They do not always turn the same way, nor with the same degree of velocity, sometimes moving in opposite directions, at other times both one way. The figure varies according to the degree of their protrusion, as well as from other circumstances. They appear occasionally like minute oblong squares, rising from the periphery of a circle; at other times they terminate in sharp points, and sometimes they are curved, bending the same way like so many hooks; now and then the ends appear clubbed, or in resemblance like a number of small mallets.

When the fore-part of this creature is first seen to open or divide, the parts, which when fully protruded resemble wheels, seem only like a couple of semicircles, the edges of which are set with little spiculæ, having a nimble, and continually vibrating motion upwards and downwards, for the purpose of agitating the water, each wheel being in this case doubled, or like a round piece of paper folded in the middle.

When the wheels are in motion, the head appears very large in proportion to the size of the animal; and though it is then everywhere transparent, yet a ring or circle, more particularly distinguished by its brightness, may be perceived about the middle of the forehead, from whence many vessels are seen to originate.

The thorax or breast is united to the head by a short annular circle or neck; the size of the thorax is nearly one-sixth part of the whole animalculum. In it the heart is distinctly seen; being placed nearly in the center, the diastole and systole cannot fail to attract the eye of every attentive observer; the alternate dilatation and contraction is very perceptible through the back of the animal, being performed with great strength and vigour. It appears to be composed of two semilunar parts, which in the time of contraction approach each other laterally, and form between them a figure somewhat like a horse-shoe, whose upper side is flat, the under one convex. In the diastole, these two parts separate; the separation begins exactly in the middle of the lower part next the tail. In each of the semilunar parts there is a cavity, which closes when they come together; and opens when they separate.

The motion of the heart is communicated to all the other parts of the thorax, and indeed through the whole animal. It is necessary however to remark, that this motion is sometimes suspended, or at least quite imperceptible, for two or three minutes, after which it re-commences, and goes on with the same vigour and regularity as before. From the under part of the thorax a small transparent horn proceeds, which cannot be seen unless the insect turns on its back or side.

Below the thorax there is an annular circle that joins the thorax to the abdomen; this is considerably the largest part of the animal, and contains the stomach and viscera. When full of food, the intestines are opake, and of a crimson colour, extending from the thorax quite through the abdomen and a great part of the tail, exhibiting a fine view of the peristaltic motion, or those gradual contractions and dilatations of the intestines, which propel their contents downwards. Numerous ramifications of vessels, both longitudinal and transverse, surround the intestines. The abdomen is not only capable of contraction, but also admits of such a degree of extension, as to form a case for all the other parts of the body. The tail extends from a joint at the lower part of the belly to the posterior extremity; it is of a tapering form, and consists generally of three joints; when the animal is inclined to fix itself to any thing by the tail, it thrusts out four, sometimes six, little hooks from the extreme part; these are placed in pairs, one at the very extremity itself, the other two a little way up the sides; the three pair are seldom seen at the same time. The wheels appear to be the organs used by the animal to assist it in swimming.

All the actions of this creature seem to imply sagacity and quickness of sensation; at the least touch or motion in the water, they instantly draw in their wheels. Baker conjectures that they have eyes lodged near the wheels, because while they are in the globular or maggot state, their motions are slow and stumbling; but after the wheels are protruded, they are performed with great regularity, swiftness, and steadiness. Can we sufficiently admire the wonderful contrivance in the apparatus of this animal? a being so diminutive, as not to exceed in size a grain of sand!

Plate XXVI. Fig. 17, represents the wheel animal in what Baker calls the maggot state; while in this form small spiculæ are seen to dart out near the anterior part; the snout is sometimes more, at other times less acute than in this delineation. a, a small horn near the thorax.

Fig. 15 represents its manner of moving from place to place, while in the maggot state. a, the projecting horn.

Fig. 12 exhibits it with the two semicircular parts, a a, protruded, and in the posture in which it places itself, when preparing to swim about, or going to set its wheels in motion.

Fig. 1 shews the head at its full extent, and a couple of small bodies, a a, on the top of it, armed with small teeth, b, like those of the balance-wheel of a watch.

At Fig. 18 the interior parts are more particularly exhibited. a, the circle from which many vessels originate; b, the thorax or breast, joined to the head by the neck, c; the part which is supposed to be the heart is plainly seen at d; the abdomen, f, is separated from the breast by a ring, e; g, the tail.

Fig. 19 exhibits the animal not fully extended, though with its wheels in motion.

Fig. 20 shews it with its side towards the eye; in this position one of the wheels, a, appears to lie considerably below the other.

Fig. 6 and 16 represent two of these creatures in the postures in which they are frequently seen when the wheels are not protruded, but with the fibrillæ, a b, vibrating quickly.

Fig. 2 exhibits the animal with the body nearly drawn into the abdomen; at Fig. 21, the body still further drawn in; at Fig. 22, as it appears with the tail partly drawn in; at Fig. 23, in a globular form, but still adhering by the tail.

Sometimes, when in the maggot form, it rolls its head and tail together, without drawing them into the body; as represented at Fig. 14.

Baker has also described three other species, one of which, differing only from the preceding in having a very long tail, is represented at Fig. 7.

Fig. 11 is another kind, with crustaceous spiculæ, b, at the fore-part; within this, at c, an opake oval body may be seen, which has been taken for an egg.

Fig. 3 is another kind; it has two projecting points, a a, from the tail, and the head furnished with a number of fibrillæ, b b.

Fig. 13 represents another species, described by Spallanzani.

Plate XXVII. Fig. 46, 47, 48, 49, represent the wheel animals seen and delineated by Müller. a, the head; b, the eyes; c, a small horn; d, the rotatory organ; e, the tail; f, the points of the tail.

324. Vorticella Furcata.

V. cylindrica, apertura integra, cauda longiuscula bifida. Cylindrical vorticella, the aperture undivided, the tail rather long, and divided into two parts.

A cylindric body with a rotatory organ, consisting of a row of hairs at the apex; the tail is divided into two parts turning a little inwards. When at rest, it joins the segments of the tail; but opens them when in motion. It is generally found in common water.

325. Vorticella Catulus.

V. cylindracea, apertura mutica, cauda perbrevi, reflexa, bicuspi. Plate XXVII. Fig. 50. Cylindrical vorticella, the aperture plain, the tail short, bent back, and divided into two points.

It is a little thick muscular animalculum, folding itself up; of an equal breadth throughout, the body disfigured by longitudinal folds winding in various directions; the anterior part or head is connected to the body by a little neck, and it occasionally exhibits a very minute rotatory organ. The tail, e, is short, terminating in two very small bristles, d, which are exposed or concealed at pleasure; the intestines ill-defined. Its motion is rotatory, but in different directions. It is commonly found in marshy waters.

326. Vorticella Canicula.

V. cylindracea, apertura mutica, cauda brevi, articulata, bicuspi. Cylindrical vorticella, the aperture plain, with a short articulated tail divided into two pointed parts.

327. Vorticella Felis.

V. caudata, cylindracea, mutica, cauda spinis duabus longis terminata. With a tail, cylindrical, beardless, the tail terminating in two long spines.

The body is large, the apex of an equal thickness, obtuse, with rotatory filaments; the tail acute, with two pellucid spines, in length about one-third part of the body, alternately separating from and approaching each other.

328. Vorticella Stentorea.

V. caudata, elongata, tubæformis limbo ciliato. Long-tailed vorticella, trumpet-shaped, the arms furnished with rows of short hairs. See this fully described by the name of hydra stentorea, in page 392.

329. Vorticella Socialis.

V. caudata, aggregata, clavata; disco obliquo. A description of this vorticella has also been given, as hydra socialis, in page 395.

330. Vorticella Flosculosa.

V. caudata, aggregata, oblongo-ovata, disco dilatato pellucido. Plate XXVII. Fig. 51 and 52. With a tail aggregated, of an oblong oval shape, with a dilated pellucid disc.

To the naked eye it appears as a yellow globule, adhering to the ceratophyllum, or common horn-wort, Fig. 52, a, like a little flower; or a heap of yellow eggs, b. With the assistance of the microscope they are discovered to be a congeries of vorticellæ, constituting a sphere from a mouldy center. They contract or extend their bodies either when alone or associated, and excite a vortex in the water by means of the disc. When they quit the society, and act singly, their parts may be more readily distinguished, and will be found to consist of a head, abdomen, and tail. The head is often drawn back so far into the abdomen, that it cannot be seen, exhibiting only a projecting, broad kidney-shaped disc. The abdomen, Fig. 51, d, is oblong, oval, and pellucid, replete with obscure intestines, amongst which are one or two remarkable black oval spots, e; the tail, f, is sharp, twice as long as the abdomen, either rough and annulated, or altogether smooth.

331. Vorticella Citrina.

V. simplex, multiformis, orificio contractili, pedunculo æquali. Plate XXVII. Fig. 53. Simple, many-shaped, with an orifice admitting of contraction, and equal-sized foot-stalk.

The head is full of molecules, round, everywhere of an equal size, and very pellucid; both sides of the orifice are ciliated, and each has a rotatory motion, appearing sometimes without the edge of the mouth, as at a a; at other times within it. No distinct intestines or internal motion are perceivable. Its motion is different from most of this genus, but not easily described; at c c are small feet. It is found in stagnant water.

332. Vorticella Piriformis.

V. simplex, obovata, pedicello minimo retractili. Simple, somewhat oval, with a very small retractile foot, which it can draw within itself.

333. Vorticella Tuberosa.

V. simplex, turbinata, apice bituberculata.

Simple vorticella, the upper part broad, the under part small, with two projections at the anterior end, furnished with a number of fibrillæ, which produce a current of water by their vibration, and thus collect food for the animal. Baker has delineated it in Plate XIII. No. 10, 11, 12, of his Employment for the Microscope.

334. Vorticella Ringens.

V. simplex, obovata, pedunculo minimo, orificio contractili. Simple, somewhat of an oval shape, with a small pedicle, and an orifice which it contracts or dilates.

The small head, or rather body of this little creature is pear-shaped, pellucid, the middle of the aperture convex, both sides ciliated, the pedicle four times shorter than the body; it can contract the orifice to an obtuse point.

335. Vorticella Inclinans.

V. simplex, deflexa, pedunculo brevi, capitulo retractili. Simple, bent, with a short pedicle, and small retractile head.

This has a pellucid pendulous little head; the anterior part truncated, occasionally contracting itself twice as short as the pedicle; its shape resembles that of a tobacco-pipe.

336. Vorticella Vaginata.

V. simplex, erecta, ovato-truncata, pedunculo vaginato. Simple vorticella, erect, of the shape of a truncated egg; the pedicle is contained in a sheath.

For the 337th, 338th, and 339th, the author refers to the Zool. Dan. he terms them, vorticella cyathina, vorticella putrina, vorticella patellina.

340. Vorticella Globularia.

V. simplex, sphærica, pedunculo retortili. Simple, spherical, with a twisted pedicle.

This animalculum has a small spherical head, the aperture of the mouth ciliated; the pedicle four times longer than the body, which it contracts into a spiral form. It is frequent among the cyclopa quadricorni.

341. Vorticella Lunaris.

V. simplex, hemisphærica, pedunculo retortili. Plate XXVII. Fig. 54. Simple, hemispherical, with a twisted pedicle.

The small head of this animalculum is goblet-shaped, the margin of the orifice protuberant, ciliated on both sides, with undulating hairs; the pedicle eight or ten times the length of the body. The pedicle extends itself as often as the mouth is opened, but is twisted up spirally when it is shut; and these motions are frequently repeated in a short space of time, a a, the head when expanded; b, when shut; c, the undulated edge; d d, the cilia erect; e, when horizontal; f, the pedicle when straight; g, when bent in a spiral form.

342. Vorticella Convallaria.

V. simplex, campanulata, pedunculo retortili. This animalculum, the bell-animal of Baker, has been fully described in page 407.

343. Vorticella Nutans.

V. simplex, turbinata, pedunculo retortili. Simple, with a twisted turbinated pedicle.

The pedicle is simple, and twists itself spirally; is extremely slender, with a kind of cap on its head; the margin white and round, and appearing as if encompassed with a lucid ring; the head diminishes towards the base. It is transparent.

344. Vorticella Nebulifera.

V. simplex, ovata, pedunculo reflexili. Plate XXVII. Fig. 66. Simple, egg-shaped, the pedicle bent back.

The body is narrow at the base, open and truncated at the top; the margin apparently surrounded with a ring; but, when the aperture is shut, the animalculum is egg-shaped, with a simple setaceous pedicle, considerably longer than the body, and generally much bent back. a a a, the head open; b, partly closed; c, quite shut; d, the stalk when straight; and at e, when bent.

345. Vorticella Annularis.

V. simplex, truncata, pedunculo apice retortili. Simple, truncated, with a pedicle twisted at the end.

This is visible to the naked eye; when contracted, it appears to be annulated; the head is an inverted cone, convex when the mouth is shut, but truncated when it is open, and with a protuberant edge; the pedicle is simple, very long and thick, whiter at the top than any other part, and formed into a little head; the apex is twisted spirally.

346. Vorticella Acinosa.

An ample description of this animalculum, under the title of vorticella umbellaria, has been given in page 402.

347. Vorticella Fasciculata.

V. simplex, viridis, campanulata, margine reflexo, pedunculo retortili. Simple, green, bell-shaped, the margin or edge turned back, the pedicle twisted.

The head is bell-shaped, green, opake, narrow at bottom, pellucid. It has a rotatory organ, which may sometimes be seen projecting beyond the aperture; there is a little head at the apex, and the pedicle is twisted and very slender. A congealed green mass, which is often swimming about in ditches, is composed of myriads of these animalcula, which are invisible to the eye, but when magnified, appear like a bundle of green flowers.

348. Vorticella Hians.

V. simplex, citriformis, pedunculo retortili. This may be classed among the most minute. The head resembles a citron, the apex is truncated, the base narrow; a gaping cleft is observable descending from the apex, to one-third of the body.

349. Vorticella Bellis.

V. simplex, hemispherica, margine contractili. Simple, hemispherical, with a margin which it can contract at pleasure.

The body is of a yellow colour, much resembling the flower of a daisy; the head scarcely pellucid; the internal part quite filled; it is abundantly ciliated round the margin, moving in a rotatory manner.

The foot or pedicle is long, slender, and pellucid; it is divided into two parts, with small knobs on the top of each; the base adheres to a bulb, the under-part is covered with small scales.

350. Vorticella Gemella.

V. simplex, sphærica, capitulo gemino. Simple, spherical, with a double head.

The pedicle is long, and constantly furnished with two small heads at its apex; these are bright and clear.

351. Vorticella Pyraria.

The distinguishing characters of this animalculum will be found at page 400.

352. Vorticella Anastatica.

A full description of this vorticella has also been given at page 397.

353. Vorticella Digitalis.

At page 406 the reader will likewise meet with an account of the v. digitalis.

354. Vorticella Polypina.

V. composita, ovato-truncata, pedunculo reflexili ramosissimo. Plate XXVII. Fig. 61. Compound vorticella, oval, truncated, with a bending branching stalk.

When viewed with a small magnifier, they appear like so many little trees; the upper part or heads are egg-shaped, the top truncated, the lower part filled with intestines; the branches are thick set with little knobs. a, the trunk; b b b, the branches; c c, the head when extended; d, the small knobs on the branches.

355. Vorticella Racemosa.

V. composita, pedunculo rigido, pedicellis ramosissimis longis. Compound, rigid pedicle, with small branched long feet.

To the naked eye it appears like the vorticella socialis, described in page 395, but is distinguished from it by always adhering to the sides of the vessel in which it is placed. With the microscope, a long very slender pedicle is discovered sticking to the sides of the vessels, from which proceed an innumerable quantity of crystalline pellucid pearls, which, together with the stalk, are variously agitated in the water. They sometimes move separately, at other times together, are sometimes drawn down to the root, and in a moment expanded again.

XVII. BRACHIONUS.

Vermis contractilis, testa tectus, ciliis rotatoriis. A worm capable of contracting, covered with a shell, and furnished with rotatory cilia.

356. Brachionus Striatus.

B. univalvis, testa ovata striata, apice sexdentata, basi integra, cauda nulla. Plate XXVII. Fig. 64 and 65. Univalved brachionus, the shell oval and striated, six notches or teeth round the upper edge, the base whole or even, without a tail.

The shell is oblong, pellucid, and capable of altering its figure. The apex, a, is truncated, with six small teeth on the edge of it, twelve longitudinal streaks down the back, the base obtuse and smooth. The teeth are occasionally either protruded or retracted; on the other side of the shell, towards the tail, there are two little spines or horns, c.

The animalculum itself is muscular, pellucid, and crystalline, often of a yellow colour; from the apex it now and then puts forth three little bundles of playing hairs, the two lateral ones shorter than the middle one; a forked deglutatory muscle, e, is perceptible; and on the under side, when the apex is drawn in, two rigid points may be discovered. It is found in sea water.

357. Brachionus Squamula.

B. univalvis, testa orbicularis, apice truncata quadridentata, basi integra, cauda nulla. Univalved brachionus, with an orbicular shell; the apex truncated, and having four teeth, the base smooth, no tail.

358. Brachionus Pala.

B. univalvis, testa oblonga excavata, apice quadridentata, basi integra, cauda nulla. Univalved brachionus, with an oblong excavated shell, four long teeth at the apex, the base smooth, no tail. It is of a yellow colour.

359. Brachionus Bipalium.

B. univalvis, testa oblonga inflexa, apice decemdentata, basi integra, cauda spuria. Univalved brachionus, the shell oblong and inflected, ten teeth at the apex, the base smooth, and a spurious tail.

360. Brachionus Patina.

B. univalvis, testa orbiculari integra, cauda mutica. Univalved brachionus, with an orbicular shell, the edges regular, and having a long beardless tail.

The patina is extremely bright and splendid; it has a large body, a crystalline and nearly circular shell, without either incision or teeth, though towards the apex it falls in so as to form a smooth notch; the body is affixed to the middle of the shell; a double glittering organ, with ciliated edges, is projected from the apex; both these organs are of a conical figure, appearing to stand on a pellucid substance, which is divided into two lobes; between these and the rotatory organ there is a silver-coloured crenulated membrane; two small claws may be discovered near the mouth. It is reckoned as one of the rarer species of vorticella, and is found in stagnant waters in the month of May.

361. Brachionus Clypeatus.

B. univalvis, testa oblonga, apice emarginata, basi integra, cauda mutica. Univalved brachionus, the shell oblong, the apex notched, the base smooth, and the tail naked.

362. Brachionus Lamellaris.

B. univalvis, testa producta, apice integra, basi tricorni, cauda bipili. Univalved brachionus, the shell extending considerably beyond the body; the base divided into three small horns, with two hairs at the end of the tail.

363. Brachionus Patella.

B. univalvis, testa ovata, apice bidentata, basi emarginata, cauda biseta. Brachionus with a univalve oval shell, two teeth at the apex, the base notched; two bristles at the tail.

The shell plain, oval, orbicular, crystalline, with the anterior part terminating in two acute points on both sides, though the intervening space is commonly filled up with the head of the animal. The head, the tail, and the trunk are very distinct; the bottom of the trunk is terminated in a semicircle, the fore-part marked with two transverse lines; it occupies the disc of the shell. The intestines are indistinct, and the tail affixed to the trunk; it is short, annulated, flexible, the middle projecting beyond the shell, the apex diverging into two very fine bristles; it fastens itself by these, and whirls about with the body erect; the rotatory cilia are not perceptible without great difficulty. It is found in marshy water all the winter.

364. Brachionus Bractea.

B. univalvis, testa suborbiculari, apice lunata, basi integra, cauda spina duplici. Univalved brachionus, the shell rather orbicular, lunated apex, smooth base, and the tail furnished with two spines.

365. Brachionus Plicatilis.

B. univalvis, testa oblonga, apice crenulata, basi emarginata. Univalved brachionus, with an oblong shell, the apex hairy, and the base notched.

366. Brachionus Ovalis.

B. bivalvis, testa depressa, apice emarginata, basi incisa, cauda cirro duplici. Bivalved brachionus, with a flattened shell, the apex notched, a hollow part at the base, the tail formed of two tufts of hair.

367. Brachionus Tripos.

B. bivalvis, testa apice mutica, basi tricorni, cauda duplici. Plate XXVII. Fig. 59. Bivalved, the apex of the shell beardless, three horns at the base, and double tail.

The body is pellucid, nearly triangular, bivalved, and open on the back of the animalculum; from the orifice proceed two little laminæ larger than the rotatory cilia; at the bottom are three or four rigid points, e f e, and a moveable tail, g, between them, divided into two filaments, which the little creature opens and shuts at pleasure; by these it fixes itself to objects. a a, the lateral cilia; b, two small laminæ; c, a deglutatory muscle; d, an opake mass.

368. Brachionus Dentatus.

B. bivalvis, testa arcuata, apice et basi utrinque dentata, cauda spina duplici. Bivalved brachionus, with an arched shell; the apex and the base are both toothed, and the tail formed of two spines.

369. Brachionus Mucronatus.

B. bivalvis, subquadrata, apice et basi utrinque mucronata, cauda spina duplici. Bivalved, somewhat of a square form; the base and apex pointed; the tail consisting of two spines.

370. Brachionus Uncinatus.

B. bivalvis, testa ovali, apice integra, basi mucronata, cauda rugosa biseta. Plate XXVII. Fig. 55. Bivalved brachionus, with an oval shell, the apex even, the base pointed, two thick bristles for the tail.

This is one of the smallest bivalved animalcula, muscular, the apex and anterior part round, the hinder part straight, terminating in a point, furnished with a hook on the fore-part, a small rotatory organ, a long tail composed of joints, and divided at the end into two bristles. It can open its shell both at the fore and hind-part. a, the shell when close; c, the posterior point; d, the animalculum; h, the tail; i, the bristles.

371. Brachionus Cirratus.

B. capsularis, testa apice producta, basi curti bicorni, cauda biseta. Larger than the preceding, ventricose, somewhat pellucid, the head conical, with a bundle of hairs on both sides; it has likewise a rotatory organ.

372. Brachionus Passus.

B. capsularis, testa cylindracea, frontis cirris binis pendulis, setaque caudali unica. Capsular brachionus, in a cylindric shell, with two long pendulous locks of hair proceeding from the front; the tail consists of a single bristle.

373. Brachionus Quadratus.

B. capsularis, testa quadrangula, apice bidentata, basi bicorni, cauda nulla. Capsular brachionus, in a quadrangular shell, with two small teeth at the apex, two horns proceeding from the base, and no tail.

374. Brachionus Impressus.

B. capsularis, testa quadrangula, apice integra, basi obtusi emarginata, cauda flexuosa. Capsular brachionus, the shell quadrangular, a smooth undivided apex; obtuse base; notched margin, and a flexuous tail.

375. Brachionus Urceolaris.

For a full description of this animalculum, being the same as the vorticella urceolaris, the reader will please to refer to page 408. Views of the animal in its different positions will be found in Plate XXII. Fig. 36, 37, 38, and in Plate XXVII. Fig. 56 and 57. Fig. 56, a a, are the two fibrillæ; b, the head; f, the intestines; i, the aperture from which the tail is protruded; i k, the tail; at the end, k, is a cleft, enabling the animal to affix itself more firmly to any substance. Fig. 57, at a c a, are seen the fibrillæ; d shews the moveable intestine, supposed to be the heart or lungs; f, the intestines; h i k, the tail.

376. Brachionus Bakeri.

B. capsularis, testa ventricosa, apice quadridentata, basi bicorni, cauda longa bicuspi. Plate XXVII. Fig. 58. Capsular brachionus, the shell ventricose, four teeth at the apex, two horns at the base, and a long tail terminating in two short points.

This differs considerably from the foregoing in the shape of the shell, from each side of which there is a curved projection, f f, inclining towards the tail, nearly of the same length with it, and terminating in a point, h h. The upper part also of the shell is of a different form, having in general four longer spiculæ, and two shorter ones. From the head two arms or branches, e e, are frequently extended; the circular end of each is furnished with a tuft of little hairs, which sometimes move in a vibratory manner, at other times have a rotatory motion. The eggs are either affixed to the tail, or the curved part of the shell; they have from one to five hanging from them. Müller has likewise discovered in this animalculum two small feelers, and a kind of tongue. a a, the rotatory organs; b, the tongue; c c, the feelers; d d, a ciliated part on the side of the shell; g, the heart or lungs; m k, the tail; at the extremity, k, two sharp points.

377. Brachionus Patulus.

B. capsularis, testa ventrosa, apice octodentata, basi lunata quadricorni, cauda brevi bicuspi. Capsular brachionus, the shell ventricose, eight teeth at the apex, the base lunated or hollowed into the form of a crescent, and furnished with four horns; the tail short, with two small points at the end.

ADDITIONAL ANIMALCULA INFUSORIA, EXHIBITED IN PLATE XXVI.

378. Fig. A A A. An animalculum found in ditch water in the month of September, represented in three different forms which it assumed.

379. Fig. B B B. A species of testaceous wheel-animal; a, its appearance when protruded; b, when in the shell; c, another appearance of the same.

380. Fig. C, shews one of the same species; and

381. Fig. D, exhibits another of the same kind; they both appear as protruded from the shell. The above are all drawn as they were found adhering to a vegetable substance.

382. Fig. E E E. Several appearances of an animalculum found in stagnant water in September, about the one-hundredth part of an inch in length; it moved slowly, and there appeared a wheel-like motion in certain fibrillæ in the head. The double-forked part of the tail had a similar motion to the tail of the pulex aquaticus; the intestines appeared of different colours, as brown, yellow, and reddish, and had a quick irregular motion; the external parts were very transparent.

383. Fig. F F F F. Several animalcula in a drop of water from a leaden cistern; of different sizes, but apparently of the same species. They moved either end foremost, without any undulating motion, but very uniform and slow; each end appeared alike, and very transparent; the middle clear, brown, with a blackish list nearly the whole length of the animal. The large one, a, lay sometime bent, as in the drawing, the others, both when in motion and at rest continuing quite straight. Some of the very small ones were transparent; others appeared as at b and c.[128]

Having in this and the preceding chapter described an extensive variety of those minute and wonderful productions of nature, the hydræ, vorticellæ, and animalcula infusoria, I shall take my leave of the subject with remarking, that though by the assistance of the microscope myriads of animated beings, roving in the smallest drop of water as if it were a sea, have been exhibited to the astonished eyes of attentive observers, it surely cannot be deemed an unreasonable supposition, that the Adorable Creator, who has filled the immensity of extent with suns and worlds, has also peopled every particle of fluid with beings far more minute than any apparatus of ours can perceive; and however insignificant many of the smaller parts of the creation may appear to the uninformed bulk of mankind, there cannot exist a doubt, but that they were all, collectively and individually, formed for the wisest purposes; and, though in many instances these designations are to us incomprehensible, let us not on that account rashly withhold our admiration. These sentiments are beautifully enforced in the following expressive lines of Thomson: