HELMINTHOLOGY.^[1. From lλμms, a worm, and λa7a5, a discourse. ] The title of this article was formerly bestowed on a much larger group of animated beings than that to which we here restrict it. The Linnaean group of Vermes contained, in fact, the whole of the intestinal and other worms, the molluscous and testaceous tribes, the Zoophytes and Infusoria,—which now form the natural materials of many classes. We here apply it exclusively to the Annelides, or red-blooded vermes, of which the medicinal leech and earth-worm afford familiar examples. Bruguieres and others have no doubt conjoined them, in comparatively recent times, with the intestinal tribes; and it was at one time our intention (see Animal Kingdom, vol. iii. p. 180 of this work) to have adopted that arrangement. But we now conceive it to be more advisable to follow the example of Cuvier, and, referring the latter to the radiated or zoophytical division, to include in the article Helminthology the Annelides alone. In truth, the intestinal tribes exhibit no organs of respiration, either tracheal or branchial,—no traces of a true circulation,—and their nervous system is extremely obscure. It will therefore become apparent, from the following definition, how greatly the Annelides differ from the creatures just named.

The Annelides or red-blooded worms form the first class of the articulated division of the animal kingdom.^[2. For a description of these primary divisions of the animal kingdom, see vol. iii. p. 179 of this work. ] Their blood, of a red colour, resembling that of the vertebrated animals, circulates in a double system of closed vessels, that is, in arteries and veins. This system, though destitute of a heart properly so called, is sometimes provided with one or more distinct fleshy ventricles. Respiration is carried on through the medium of organs, which are sometimes external, occasionally developed beneath the surface of the skin, or sunk more deeply into the interior. They may all be presumed to breathe by means of branchiae, although the respiratory system, of the so-called Abranchial Order, is still unknown. The branchiae or respiratory organs of the greater number are external, and vary considerably in their size, form, number, and position. Their body, of a softish texture, is more or less elongated, and always divided into numerous rings or segments, of which the anterior, known under the name of head, scarcely differs from the others, except by the possession of a mouth, and of the principal organs of the senses. None of the Annelides possess articulated members properly so called, but in room of these many are furnished with setiferous mammillae, or fleshy projections, bearing bundles of hairs or bristles, and forming what may be called pedes spurii, of which the number is extremely various. These peculiar organs are sometimes composed of two parts, the one superior and dorsal, the other inferior and ventral. The muscular power resides in the interior, and is capable of producing only an undulatory or creeping movement,—the locomotive parts being incompetent to sustain the body. The organs of the mouth consist sometimes of parts resembling jaws, more or less developed,—sometimes of a simple tube. The organs of the external senses are composed of fleshy tentacula, sometimes articulated,—and of certain blackish points, not existing in all the species, regarded as eyes. The nervous system consists of a double ganglionic cord, analogous to that of insects, as already described in our article Entomology. In regard to their natural habits, most of these creatures are aquatic (the Lumbrici or earthworms excepted). Some dwell in holes beneath the waters, other form tubes or tunnels of mud or other matters, or even transude from their own bodies a calcareous secretion, which forms around them a protecting covering.^[3. “As to the external tube which the Chetopoda (by which term Μ. de Blainville denominates the setigerous genera of the class Annelides) often inhabit, although it is frequently sufficiently regular and solid, it cannot however in any manner be compared to the shell of the Mollusea, not even where there is the greatest approximation, as in Dentalium and Siliquaria. These tubes of the Chetopoda are always simple excretions from their body, which are by no means attached to it, and from which the animal may issue forth without dying immediately. We begin to observe something of this kind in the mucosity with which certain species line the hole hollowed in the mud or sand which they inhabit, as in the Arenicoae, and some Lumbrici. This is analogous to the mucous pellicle of the tube of the Amphitritae and the Sabellae; but in the latter, surrounding this mucosity, is attached externally a stratum, more or less thick, composed merely of mud or very fine grains of sand, or, in fine, of debris, more or less thick, of shells and larger grains of sand. These tubes are constantly open at both extremities; there are also some of them more regular, which are completely calcareous. The double opening is a character whereby they are distinguished from tubular shells, the summit of which, on the contrary, is constantly imperforate. These tribes, however, appear constantly to grow, after the manner of tubular shells, by laminae or strata extremely thin, placed inside of and out-edging one another. From this result striae marking the growth, more or less apparent outside·; but we never remark longitudinal striae on their surface, nor anything indicating the delicate working of the edges of a mouth, as in the Mollusea. This character alone might suffice to distinguish them from the true tubular shells ; but to this we may add, that the constant perforation of the summit of the tube of the Chetopoda never allows the animal, in growing and advancing in its tube, to form partitions there, whereas in the tubular shells the reverse is invariably the case. A final character which distinguishes the tubes of the Chetopoda is, that they are adherent, and fixed flatly, through a greater portion of their extent, on foreign bodies, which never takes place with the tubular shells.” (Griffith’s edition of Cuvier’s Animal Kingdom, vol. xiii. p. 58.) We may add, that the young of the shell-bearing Mollusea are always born with shells, because that part forms, in fact, a portion of their skin; but there is no doubt that the young Annelides are produced in an exposed condition, and afterwards proceed, by a voluntary effort, to form their protecting habitations. ' ] Considered sexually, they are for the most part hermaphrodite, and some require reciprocal communication.

It will be perceived, even from the preceding brief exposition, that the Annelides are animals of a very peculiar nature. Although their nervous system coincides with that of the other articulated classes, and although their bodies are likewise divided by transverse sections, yet their locomotive organs are entirely dissimilar to those of the Crustacea, Arachnides, and Insects. Their setiferous mam-millae are merely retractile sheaths, and the hairs or bristles which they enclose are in no way comparable to the feet of the last-named classes, but are organs of a very different nature.

The Annelides are few in number compared with insects and other articulated classes, and the greater proportion are marine. Their possession of red blood is a singular character in animals so low in the scale, and one not possessed by the molluscous tribes, which are yet regarded as their superiors in other points of organisation. In regard to their external parts, we shall here indicate a few of the most important,—premising that the characters mentioned are not universal to the class, but rather [7:11:217]confined to certain races. The head, in such as possess one, is a small anterior swelling, which bears the antennae commonly so called, and the eyes, and is distinct from the first segment of the body. The Nereids of Linnaeus are regarded by Latreille as the only Annelides of which the anterior segment merits the name of head, or possesses organs fit to be compared to eyes, more especially to those of the larvae of insects. These eyes are simple, extremely small, and appear like blackish points,—their number from two to four. Savigny indeed attributes eight to the leech tribe, but Latreille suspects that their structure is different from that of the Nereids. The organisation of the mouth varies greatly in the different orders. The parts called maxillae by Savigny are hard circumscribed parts, of a corneous or calcareous nature, to which Latreille does not accord the name of jaws. The latter author indeed seems to regard the Annelides as a suctorial rather than a masticating class. Most of them are of carnivorous habits, and live on the blood of other creatures. The trunk or sucker is a contractile fleshy portion, constituting the mouth, and containing the so-called jaws. The latter portions, however, being adherent to the inner coats of the sucker, and the latter being nothing more than a prolongation of the oesophagus, can scarcely be regarded as genuine jaws.

Several tribes have their branchiae uniformly spread over the extent of the body, or over its central portion, while others (and these usually dwell in tubes) bear those organs at their anterior extremity. In the erratic species, or such as are naked, and without fixed dwellings, they are usually disposed longitudinally along the sides of the body, there being one for each foot. Blood-vessels sometimes appear to spread into the setiform processes, and to convert them into respiratory organs.

We have already stated that Linnaeus placed the Annelides in his almost unlimited class of Vermes,—a vast and by no means well-combined group, which the later labours of Otho Frederick Muller, Pallas, and other naturalists, failed to cast into a more natural mould. The great Swedish naturalist separated the true Annelides from each other, placing one portion of the group in the order Intestina, and the other in that of Mollusea. In Cuvier’s earliest work (Tableau Elémentaire, 8cc. 1789), he restricted the class of worms to the Annelides and intestinal species, a mode of grouping previously practised by Bruguieres in the Encyclopédie Méthodique. Subsequent investigations induced the French anatomist to raise the former to the rank of a separate class, which he named Vers a sans rouge, in a memoir read to the French Institute in 1802. On this same group Lamarck (Extrait du Cours, &c. 1812) bestowed the name of Annelides, which has since been very generally adopted. A slight disparity, however, still exists in the constitution of the Annelides, in the works of Cuvier and Lamarck, the former including in the class so named the genus Gordius, which the latter associates with the other Vermes.

But notwithstanding the valuable labours of these and other writers, the external structure of the Annelides cannot be said to have been at all rigorously determined, or viewed in relation to that of conterminous groups, till we received the fruits of Savigny’s laborious and most delicate observations, originally presented to the Academy of Sciences.^[4. Système des Αηnelides, forming a portion of the great French work on Egypt. ] At that period Blainville was also occupied in the study of the same group, which, with the exception of the leeches, forms his class of Setipodes. He published an extract from his labours in the course of the ensuing year.^[5. Bulletin de la Soe. Phil. Mai eţ Jurn 1818. ] Oken, Leach, Latreille, Dugés, Audouin, Mylne Edwards, and others, have likewise contributed to our knowledge of this curious and important class, in publications, to the majority of which we shall more particularly allude in the course of the present treatise.

In regard to the geographical distribution of the Annelides, our data are not yet sufficiently precise and numerous to admit of any satisfactory generalization. We have already said, that with the exception of the earthworms (and even these require a moist abode), all the known species are aquatic. We may add, that the great majority inhabit the saline waters of the ocean. Most of the Naids, however, occur in fresh water, and some true Nereids are found in the lakes of North America. Annelides of some kind or other are met with in all quarters of the globe, and the species of many genera are very widely distributed; but others, such as the Amphi-nomoe, for example, are characteristic of, if not peculiar to, the warmer seas. Undoubtedly the most magnificent are native to the Indian shores. “It is in general on the coasts of the sea, in the midst of Thalassiophytes, in the anfractuosities of Madrepores, in the sand, and particularly in mud, that the Chetopoda are to be found; and if some species are more commonly to be met with in the open sea, as, for instance, the Amphinomae, named by Μ. Savigny Pleione vagans, it appears that they may have been drawn along with marine plants by the currents, as is the case with many other animals.”^[6. Griffith’s Animal Kingdom, vol. xiii. p. 73 « ] Their natural movements are extremely slow, and maybe compared to those of slugs, although their appendages for locomotion are much more numerous. The Nereids, however, not only creep in a kind of serpentine manner over the surface of solid bodies at the water’s edge, but frequently swim very respectably, either by successive undulations of the body, after the manner of eels and serpents, or by agitating their appendages, and thus making these organs serve as oars.^[7. The lateral parts are hence named rames by Μ. Savigny. ]

The utility, in an economical point of view, of the Annelides in general to the human race, is by no means great. According to Pallas, the inhabitants of some parts of Belgium eat those portions of Aphrodita aculeata which compose the mouth; the Nereids and Arenicoae, as well as the earth-worms, are extensively employed as baits for fish, and the medicinal uses of the leech are notorious; but, with these, and, it may be, a few other exceptions, little can be said regarding the direct benefits derivable from this peculiar class. Its subjects, howèver, are by no means on that account the less important in the eyes of the philosophical naturalist.

Several of the Annelides possess a phosphoric property, from which Linnaeus named a certain species Nereis noctiluca. Others, characterized by the same attribute, have been more recently described by Sig. Viviani.^[8. Phosphorentia mans quatuordecιm lucescentium ammalculorum novis specieims illustrata. Genuae. 1805. ]

The presence or absence of the organs of motion, and the position of the branchiae, furnish natural characters of easy application, which modern zoologists have employed to signalize the primary groups. Lamarck divides the Annelides into three orders, les Apodes, les Antennes, and les Sédentaires,— and in the system of Cuvier they likewise form an equal number of orders, les Tubicoes, les Dorsibranches, and les Abranches. In both systems the Serpulae occupy the highest position in the scale. Savigny’s arrangement of these animals consists of five orders, of which the author has as yet treated only of four, viz. les Nereidees, les Serpulees, les Lombricines, and les Hi- [7:11:218]rudinées. He places the Aphrodites and Nereids at the head of the class. Latreille is also of opinion that these Annelides, especially the Nereids, so far as regards their external organisation, are entitled to precedence, and make the nearest approach to the articulated animals provided with feet, such as Insects and Crustacea.

We shall here, in as far as general arrangement is concerned, follow the system of Cuvier.

Order I.—TUBICOLAE, Cuv.

Some form a calcareous homogeneous tube, supposed to result from transudation, like the covering of testaceous Mollusea, but which does not adhere by any muscular attachment; others construct a covering by agglutinating grains of sand, broken shells, and other debris, by means of a membrane, likewise the result of transudation; while a third group are surrounded by a tube of an entirely membranous or corneous nature.

Genus Serpula, Linn. The body is composed of numerous segments; its anterior portion is enlarged in the form of a disk, armed on either side by several bundles of stiff bristles; and on each side of the mouth is a fanshaped plume of branchiae, usually adorned by lively colours. At the base of each plume is a fleshy filament, one or other of which is always prolonged and dilated at the extremity into a disk of various form, which serves as an operculum, and closes the overture of the tube whenever the contained creature chooses to retire. (Plate CCLXXV. fig. 3.) Of this genus the calcareous tubes cover, by their tortuous windings, the surface of stones, shells, and other submarine bodies. The species are widely distributed throughout the seas of Europe, India, and America. The largest are indigenous to the warmer climates of the globe. Little is known of their instinctive habits or natural economy. They arc said to feed on aquatic animalcules, which they seize by means of their branchial tentacula.

Linnaeus, and most of the naturalists of his time, placed the Serpulae among the testaceous Mollusea. They now constitute a numerous genus, of which several species occur in the European seas. They are very contractile, and are supposed to feed on animalcules. A well-known species, 8. contortuplicata (Plate CCLXXV. fig. 1), has rounded tortuous tubes, of about three lines in diameter. Its operculum is tunnel-shaped, and its branchiae are often of a beautiful red, or varied with yellow and violet. Any object thrown into the sea is apt to be speedily covered by this species.

Genus Spirorbis, Lam. Branchiae much less numerous than in the preceding genus (from three to four on each side), placed anteriorly in a somewhat radiated form. A pediculated operculum, with a flat summit placed between the branchiae. Tube testaceous, and rolled after the manner of a Cornu ammonis.

This genus is composed of very small species, which are found attached to fuci, shells, and other marine bodies. They frequently occur in great numbers, though always separate from each other. The animals are of a blood-red colour. We have figured the Sp. nautildides of Lam. synonymous with the 8erpula spirorbis of Linn. See Plate CCLXXV. figs. 2 and 4.

Genus Sabella, Cuv. Amphitrite, Lamarck. Body and fan-shaped branchiae resembling those of the preceding genus, but both the fleshy filaments adhering to the branchiae terminate in a point, and do not form an operculum; they are sometimes even wanting. Their tube is rarely calcareous, and seems often formed of grains of very fine clay or mud. Most of the ascertained species are of considerable size, and are remarkable for the extreme delicacy and lustre of their plumy branchiae.

One of the most splendid of the genus is figured by Dr Shaw under the title of Tubularia magnifica. ^[9. Linn. Τrαns. v. p. 228, tab. 9. ] It is found on various parts of the coast of Jamaica,’ adhering to the rocks. It is extremely wary, and when approached instantly recedes within its tube, which on a further alarm also retires into the rock, so that specimens can be obtained only by breaking off portions of the mass. These, when put into tubs of sea water, may be preserved for months, and the habits of the animals attentively studied. The species in question is characterized by a simple undulated tube of a whitish hue, the tentacula being varied by beautiful alternate bands of red and white. Amph. vesiculosa is a British species described by Montagu.^[10. Ibid. xi. p. 19, tab. 5. ] The internal texture of its tube is coriaceous, but the outer coat is invariably covered by coarse sand, intermixed with fragments of shells. (See Plate CCLXXV. fig. 5.) Considerable variety exists in the form and aspect of the genus Sabella.

Genus Terebella, Cuv. These, like the preceding, inhabit a tube of their own formation, but composed of coarser materials than that of the generality of Sabellae. Their body presents much fewer segments, and the head is otherwise adorned. Numerous filiform tentacula, capable of great extension, surround the mouth; and on the neck are placed the branchiae, which are not fan-shaped, but in the form of little branches.

The animals of this genus, according to Montagu, either prepare a sheath from the tenacious secretion of their own bodies, mixed with adventitious matters, or reside in prepared perforations at the bottom of the sea. Their tubes are in general so extremely fragile as to be easily destroyed, and the animals are then found lurking beneath stones, or forming a new dwelling. Some fabricate their tube in old shells or stones, to which they adhere by their entire length, while others fix a tube perpendicularly in the sand. These tubes are indeed frequently observed to obtrude several inches above the surface of the soil, and when the waters flow, the gills and other appendages are stretched forth, and seem agitated to and fro. The gills or branchial appendages are extremely sensible, of a fine blood colour, and when touched they contract so suddenly as to expel the fluid which they contain, and then they lose their sanguine hue. Many are gregarious, and so numerous, that the sea-shore is sometimes seen covered by their fragments after a storm. When their tubes are entire, but a small portion of’ the body is protruded, with the exception of the filiform tentacula, which they thrust about in all directions as if in search of food. The branchial appendages, just mentioned as so finely coloured during life, lose their brightness from day to day as the animals become sickly in confinement.

T. gigantea, Mont, the largest of the senus, measures sixteen inches in length, and occurs, though rarely, on the Devonshire coast. We here figure as an example another species, which has likewise been taken on that coast by deep dredging, viz. T. nebulosa of Montagu. See Plate CCLXXV. fig. 8.

Genus Amphitrite, Cuv. Pectinaria, Lam. Recognizable by the golden coloured bristles ranged in a coronal or pectinated manner, in one or more rows, on the anterior portion of the head, where they probably serve [7:11:219]• either as a means of defence, for the purposes of locomotion,^[11. Montagu observed Terebella venustula fixing its tentacula, and then, by contracting them, draw its body forward. ] or for collecting the materials of their dwelling. Numerous tentacula surround the mouth, and at the commencement of the back, on either side, there are combshaped branchiae.

The gills or branchial appendages of this genus are attached to the anterior part only of the body; and this is the case in fact with all the tribes that inhabit tubes, because gills attached to the other parts of the body, which are covered, would be useless for the purposes of respiration.^[12. Griffith’s Animal Kingdom, vol. xiii. p. 88. ] Certain species construct very light and delicate tubes, in the form of a lengthened cone, which they carry along in the course of their travels. Their golden bristles form two combs, the teeth of which are directed downwards. Their intestine is very ample, folded several times, and is usually filled with sand. À well-known European species is the Amph. auricoa Belgica of Gmelin, of which we have given two representations. (See Plate CCLXXV. figs. 6 and 7.) Its tube measures about two inches in length, and is formed of little rounded grains of various colours. Other species attach their tubes to different substances, and their golden setae form upon the head several concentric crowns, from which an operculum is produced, which closes the tube when the animal is in a state of contraction. Each foot is furnished with a cirrhus, and the body, terminating posteriorly in a tube curved towards the head, is provided with a kind of muscular gizzard.^[13. These species form the genus Sabellaria of Lamarck, and Hermella of Savigny. No department of natural history is more darkened by a confused cloud of synonyms than that which treats of the Annelides. “Ces perpétuels changements des nonis,” says Cuvier, “finiront par rendre l’étude de la nomenclature beaucoup plus difficile que celle des faits.” {Règne Animal, t. iii. p. 195.) ] To these belong Amph. alveolata, Ellis, Corail. 37, of which the tubes, combined in a compact mass, present regularly disposed orifices, resembling the cells of a piece of honeycomb. Another species, Amph. ostrearia of Cuvier, forms its tubes on the shells of oysters, and is said to be extremely injurious to the increase of that valuable mollusc.

Cuvier has placed in this order of Annelides the singular genus Syphostoma, first made known by Dr Otto, in a dissertation published at Breslau in 1820. (See Plate CCLXXV. figs. 12 and 18.) It appears to have two anterior openings or mouths.^[14. See the article Sipliostome, in the Did. des Sciences Nat. ] Here also, but with a more doubtful claim, the genus Dentalium is allowed to stand. Its covering is a solid calcareous shell, in the form of an arched elongated cone, open at both ends, and compared by some to a small tusk of an elephant. (See Plate CCLXXV. fig. 9.) The animal itself does not appear to be in any way articulated, nor to possess lateral setae. Its body is of a conical form like that of the shell, and is very smooth and compact.^[15. See Savigny, Système des Annelides, p. 98; and Deshayes, Monographie du Genre Dentale, in Mim. de la Soc. d’Hist. Nat. de Parris, t. ii. p. 321. Ŵe may here note, that the genus Dentalium seems to have been equally abundant in ancient as in modern times,— many of the calcareous tubes being found in a fossil state. ] Order II.—DORSIBRANCHIA.

The genera of this order bear their branchiae throughout the length of their body, or are at least along its middle portion, and in the various forms of branches, tufts, plates, or tubercles, in which the sanguineous vessels ramify. The majority of the species live in the mud, or swim freely in the sea. A few dwell in tubes.

Those in which the branchiae are most highly developed are∙placed at the head of the order.

Genus Arenicoa, Lam. Branchiae numerous, complicated, bush-shaped, and disposed over the intermediate segments of the body. Mouth terminal, in the form of a dilatable fleshy trunk, without either teeth or tentacula. No apparent eyes. The posterior extremity wants both the branchiae and the bundles of setae with which the other segments are furnished. There are no cirrhi to any part of the body.

This genus was established by Lamarck, at the expense of the old genus Lumbricus of Linnaeus. The best-known species, A.piscatorum (Lum. marinus, Linn.), Plate C CLXX V. fig. 10, measures about a foot in length, and bears thirteen pair of branchiae. It is of a reddish colour, and when handled it stains the fingers of a fine yellow. It inhabits moist sand by the sea-shore, and is much used as a bait by fishermen.

Genus Amphinome, Brug. A pair of branchiae on each segment of the body, and two bundles of setae, and a pair of cirrhi to each foot. The sucker is destitute of maxillae.

This genus was formed by+ruguieres from Aphrodita of Pallas and Terebella of Gmelin. Savigny divides it into three, viz.

Isí, Gen. Chloeia, containing such as have five tentacula to the head, and branchiae in the form of tri-pinnate leaves. We have figured as an example (Plate CCLXXV. fig. 13) a large and beautiful species, C. capillata, remarkable for its long and thick-set bundles of setae of a brilliant yellow, and its purple branchiae. It inhabits the Indian Seas. 2<7, Gen. Pleione, containing those species which, with the same number of tentacula, have tufted branchiae. 3ćZ, Gen. Euphrosine, containing species characterized by bushy branchiae, of a complicated structure, and strongly developed (Plate CCLXXV. fig. 11). The head is furnished with only a single tentaculum. The known species inhabit the Red Sea.

Genus Eunice, Cuv. Leodice, Sav. Branchiae in the form of plumes, but the mouth or trunk is armed with three pair of corneous maxillae of different forms. Each foot has two cirrhi and a tuft of setae. The head bears five tentacula placed above the mouth, and two on the nape of the neck. (Plate CCLXXV. fig. 16.) Some of the species are furnished with a pair of eyes.

This genus contains a monstrous worm, Eun. gigantea, Cuv. the largest of all known Annelides. It measures from four to six feet in length, and its body consists of 448 segments. Its colour is ashy grey, with an opalescent reflection. It inhabits the Indian seas. Montagu (in Linn. Trans, vol. xi. pl. 3) has figured and described a species, under the title of Nereis sanguinea, but which, from the author’s description of the jaws, is no doubt referrible to the present genus, or rather to that subdivision of it called Marphysa by Savigny, and distinguished by the absence of nuchal tentacula. The body is long, slightly depressed beneath, and its segments exceed 270, about forty of which, at the posterior extremity, were of a much paler colour than the others, and appeared to Montagu as if they had been lately reproduced. The rest of the body was of a fine bronze colour, resplendent with changeable prismatic tints. It is a large species, measuring fourteen or fifteen inches in length. Eun. tubicoa inhabits the North Sea, and is remarkable for dwelling constantly in a solid corneous transparent tube. See Plate CCLXXV. figs. 14 and 17.

After the preceding genera of the dorsibranchial order, of which the branchiae are complicated, Cuvier places those [7:11:220]of which the respiratory organs are reduced to simple laminae, or even to slight tubercles. In some species indeed the branchiae are represented by cirrhi alone.

Some exhibit an alliance to the genus Eunice, in the strength of their jaws, and the unequal number of their antennae. Such are the genera Lysidice and Aglaura of Savigny.

Genus Nereis, Cuv. Lycoris·, Sav. .Tentacula of even numbers, attached to the sides of the base of the head, and a little further onwards two others biarticulate, with a pair of simple tentacula between them. A single pair of maxillae in the proboscis. Branchiae composed of small plates, in which a net-work of sanguineous vessels is disposed. Each foot is moreover provided with two tubercles, two bundles of setae, and an upper and under cirrhus.

“The Nereides,” it is observed in Mr Griffith’s Supplement, “most usually live in the excavations of littoral rocks, in the hollows of sponges, in certain alcyones, in univalve or bivalve shells, in Madrepores, in the interstices of the radicles of Thalassiophytes, under stones, and in general in all bodies which present fissures more or less profound. There are some which bury themselves in mud or sand, where they excavate a lodge proportional to the dimensions of their body, and sometimes they line this dwelling with a mucous matter issuing from their body, in sufficient abundance to construct a tube or sheath. From this they put forth a greater or less portion of their body, but rarely the posterior extremity, so that they may be able to reenter on the slightest indication of danger. They all appear to feed upon animal substances, whether in the living state, or in a state of putrefaction more or less advanced. Μ. Bose, who has observed the manners of some species on the coasts of the United States, tells us positively that these animals feed upon polypi and small worms, on which they throw themselves, by darting the anterior part of their body, which they have first contracted. Otho Fabricius tells us of some species of Spio, or Nereides with tubes, that they seize the planariae on which they feed, by means of their long tentacula.”

The species of this genus have a linear shaped body, more or less convex above, and composed of numerous segments. The term Sea scolopendree, sometimes applied to them, expresses not inaptly their usual form. (See Plate CCLXXV. fig. 15.) N. margaritacea of Leach is distinguished by its pearly body, terminated by two long setae. Its head is tri-lobate, with eight tentacula. This species is common near the Bell Rock, and is subject to great variation of colour.

Near the preceding Nereids may be classed several genera of the same slender form, and with branchiae reduced to simple plates, or even to threads or tubercles. In some the maxillae and tentacusa are absent.

Genus Phyllodoce, Sav.^[16. Not to be confounded with the genus so named by Ranzani (in Mem. di Storia Natur. dec. prima, pl. i. fig. 2-9∖ at a period nos-tenor to the publication of Savigny’s work. t’ v ] Tentacula on the side of the head, in equal numbers, with four or five smaller ones in advance. Eyes apparent. Trunk large, and provided with a circle of very short fleshy tubercles. No apparent jaws. Branchiae broad, and in the form of leaves, thin, flat, and veined. Body linear, with many segments.

Ph. laminosa, Sav., is almost cylindrical, and consists of from 325 to 338 segments. It is of a brown colour, with reflections of purple and violet. Though nearly a foot long, it measures only a line and a half in breadth. It inhabits the shores of Nice. The Nereis lamelligera Atlantica of Pallas^[17. Nov. Αci. Ρetrορ. t. ii. p. 233, tab. 5. ] is probably a Phyllodoce.

Genus Alciopa, Aud. and Edw. Mouth and tentacula resembling those of the preceding genus, but the feet or organs of movement present, in addition to the tubercles which bear the setae and foliaceous cirrhi (branchiae), two branchial tubercles, which occupy the upper and under margins.

Genus Spio, Fab. Body slender, with two very long tentacula resembling antennae; head furnished with eyes; branchiae on each segment of the body, in the form of a simple filament.

The species of this genus occur chiefly in the North Sea. They are of small size, and dwell in membranous tubes. They continually agitate their long tentacula. We have figured as an example the N. crenaticonis of Montagu,^[18. Linn. Trans, xi. tab. 14, fig. Ú (not 3, as in the author’s references to his own figures). ] the characters of which will be better understood by an inspection of Plate CCLXXVI. figs. 1 and 1 β , than by the most laboured description. The tube of this species is extremely tender, being composed of minute adventitious matter slightly agglutinated. It is usually attached to Sertulariae. In general the feelers or tentacula are alone displayed; these are kept in constant motion, and are turned about in all directions, although they are at the same time capable of instantaneous contraction.

Genus Syllis, Sav. Tentacula of uneven number, and moniliform, in common with the superior cirrhi of the feet. The latter very simple, with a single tuft of setae.

Some diversity seems to exist in this genus in regard to the presence or absence of jaws, a character, however, of too great importance, it may be supposed, to admit of such extreme variation in a natural group. The segments of the body are very numerous.

S. monilaris, Sav. (Plate CCLXXVI. fig. 2), inhabits the Red Sea. Its body is long (consisting of 341 segments), slightly depressed, insensibly narrowed towards the tail, which terminates in two slender moniliform threads.

Genus Glycera, Sav. Recognizable by the form of the head, which bears the shape of a fleshy conical point, resembling a little horn, and of which the summit is divided into four scarcely perceptible tentacula. The maxillae are alleged to vary as in the preceding genus.

Few of the species have been observed in a recent state. G. uniconis is supposed by some to be identical with the Nereis alba of Muller and Gmelin. Its native country is unknown. G. Meckelii of Audouin and Edwards occurs on the shores of France.^[19. Lition. de la France, Annelides, pl. vi. fig. 1. ] Genus Nephthys, Cuv. The species of this genus are distinguished by a trunk resembling that of Phyllodoce, but they want the tentacula, and have on each foot two bundles of setae, widely separated, with an intermediate cirrhus.

The only species admitted by Savigny is N. Hombergii, discovered by the gentleman whose name it bears, near Havre de Grace.

Genus Lombrinera, Blainv. Tentacula wanting. The body, which is extremely elongated, bears on each segment merely a little forked tubercle, from which issues a small bundle of setae.

To this genus are referrible, among other species, the Nereis ebranchiata of Pallas,^[20. Nov. Ací p etrop , t fi. pl , vi ∙ fig . 2. ] and the Lumbricus fragilis of Muller.^[21. Zοοl. Dan. pl. xxii. ] The latter forms the doubtful genus Scoletorna of Blainville.

Genus Aricia, Sav. Teeth and tentacula wanting. Body elongated, with two rows of lamellar cirrhi on the back. Anterior feet furnished with dentated crests, which are absent from the other organs of movement.

Genus Hesione, Sav. Body short, thickish, composed [7:11:221] of few segments, and these not very distinguishable. A very long cirrhus, probably performing the functions of branchiae, occupies the upper part of each foot, which has also another beneath, and a tuft of setae. The sucker is large, but unprovided with either teeth or tentacula.

The species, though few in number, seem pretty widely distributed. II. splendida, Sav.^[22. Ouvrage d’Egypte, pl. iii. fig. 3. ] (Plate CCLXXVI. fig. 3), occurs on the coasts of the Red Sea, and was found by Mathieu at the Isle of France. II. festiva greatly resembles the preceding, though of smaller size. It was discovered in the neighbourhood of Nice, by Μ. Risso.^[23. Eur. Merid. t. iv. p. 418. ] Genus Ophelia, Sav. Body thick and short, with the segments not very apparent, and the setae scarcely visible. For two thirds of its extent long cirrhi serve as branchiae. The palate contains a toothed crest, and the lips are surrounded by tentacula, of which the two upper are larger than the others.

0. biconis, Sav. discovered by Orbigny, seems the only species yet distinctly known.

Genus Cirrhatulus, Lam. A very long branchial filament, and two small tufts of setae on each segment of the body. These segments are very numerous and closely set, and there is an additional range of filaments on the posterior part of what may be called the neck. The head, but slightly apparent, has neither jaws nor tentacula.

To this genus Lamarck (under the name of C. borealis) refers the Lumbricus cirratus of Otho Fabricius.^[24. Fauna Groenlandica. n. 281. fier. 5. ] Cuvier considers the Terebella tentaculata of Montagu^[25. Linn. Trans. ix. pl. vi. fig. 2. ] as likewise being a species of Cirrhatulus. See Plate CCLXXVI. fig· 4 ∙

The body of this marine Vermis is long and slender, and composed of more than 200 annulations, each of which is furnished with two fasciculi of very minute bristles. There are no eyes, and the branchiae are obscure. From the sides of the segments issue very long, red, capillary appendages, most numerous near the anterior end, the extreme point of which, however, is destitute of them, and becomes acuminated. The mouth is placed on the inferior face. The posterior end is likewise obtusely pointed. The length of this animal is eight or nine inches. The colour of the upper portion is olive green, of the under dull orange. While in a state of nature, the filiform appendages of the sides are in continual motion, appearing like slender red worms, twisting themselves around the body in all directions. This curious species was taken from a piece of timber that had been perforated by Pholades, and was destitute of any natural covering.^[26. Ibid. p. 110. ] Although Montagu placed it in the genus Terebella, he expressed his doubts as to the genus to which it really belonged.

Genus Palmyra, Sav. Setae of the upper tufts large, flattened, fan-shaped, and shining with the brilliancy of polished gold; under tufts small. Cirrhi and branchiae not much developed. Body elongated, with two rather long and three very short tentacula.

The only known species is P. aurifera, a native of the Isle of France, from whence it was sent to Paris by Μ. Mathieu.

Genus Aphrodita, Linn. Distinguished by its two longitudinal ranges of broad membranous scales, which cover the back, and beneath which the branchiae, in the form of little fleshy crests, are concealed.^[27. In the opinion of some observers, the Aphroditae offer an exception to the characters of their class, in not being possessed of red blood; but Cuvier has stated his belief {Règne Animal, t. iil. p. 180, note) that that feature is distinguishable in Aph. squamata. ]

The form of these Annelides is usually flatfish, and is shorter and broader than in most of the genera. The in-, terior contains a very thick and muscular oesophagus, susceptible of being in part protruded outwards, like a trunk or sucker; there is likewise an unequal intestine, furnished on each side with a great number of branched caeca, of which the extremities are attached between the bases of the tufts of setae, which serve as locomotive organs. It is alleged that the sexes are separate in the Aphroditae, and that the females are oviparous. At certain periods the female is certainly found filled with egg-like substances, which swim in a circumambient liquid, and the male is said to abound with milt.

Savigny has raised this genus to the rank of a family, containing three genera, viz. Palmyra, already noticed, Hali-thea, and Polynoe.

To the genus Halithea belongs a well-known British species, Aph. aculeata, Linn. It is of an oval form, six or seven inches in length, and nearly two inches broad. The scales of the back are covered, and in part concealed, by a substance resembling tow, which takes its growth from the sides. From these sides also spring groups of strong spines, which partially pierce through the tow-like substance, and bundles of softer and more flexuous bristles, which shine with the brilliancy of gold, or exhibit the various tints of the rainbow, scarcely yielding in beauty, as Cuvier has observed, either to the lustrous plumage of the humming-bird, or the sparkling of precious gems. Lower down is a tubercle, from which spines issue in three groups, and of three different sizes, and lastly, a fleshy cone. There are forty of these tubercles on each side; and between the first two there are a pair of small fleshy tentacula. There are fifteen pair of broad scales, sometimes pursed, upon the back, and fifteen small branchial crests on each side. This curious creature is known along our native shores by the name of sea-mouse. Two other species, Aph. sericea and hystrix, are referrible to the same genus.

Another subdivision of the Linnaean. Aphroditae has none of the flax-like substance on the back—the tentacula are five in number—and the trunk encloses strong corneous mandibles. (Plate CCLXXVI. fig. 5.) It is named Polynoe by Savigny, and contains most of the old species described by Linnaeus, Pallas, Muller, and Otho Fabricius. The Aph. clava of Montagu^[28. Linn. Trans, ix. pl. vii. fig. 3. ] is a Polynoe. Several other generic groups have been recently formed by Audouin, Milne Edwards, and others, from the genus Aphrodita.^[29. See Règne Animal, t. ill. p. 207∙ ] Genus Chaetopterus, Cuv. Mouth with neither trunk nor sucker, provided above with a lip, to which are attached two or three small tentacula. Then follows a disk, furnished with nine pair of fe'et, followed by a couple of long silky bundles like wings. The lamelliform branchiae are attached rather to the under than the upper portion, and prevail along the middle of the body.

There is only one species of this singular genus, Ch per-gamentaceus, Cuv. which measures from eight to ten inches in length, and inhabits a tube formed of a substance resembling parchment. It occurs in the West Indian seas.^[30. For descriptive notices (with figures) of several rare and otherwise interesting British Annelides, consult a series of papers published in the Magazine of Natural History (chiefly volumes 6th and 7th), by an ingenious observer, Dr Johnston of Berwick. ] Order III—ABRANCHIA.

In this the third principal division of the Annelides there is no apparent external organ of respiration. Certain species, [7:11:222]like the earth-worm, seem to respire over the entire surface; others, like the leech, by interior cavities. We perceive a circulating system of closed vessels, generally filled with red blood, and a nervous knotted cord, as among the preceding groups.^[31. See Μ. Ant. Duges Sur l’Anat∙ et Phys, des Annel. Abraneh. in Ann. des Sciences Nat. for Sept. 1828. ] Some are furnished with setae, which aid the locomotion, while others are destitute of these parts; from whence arises a subdivision into two principal families.

FAMILY I—ABPvANCHIA SETIGERA.

These are furnished with setae, and correspond to the two genera Lumbricus and Nais of Linn.

Genus Lumbricus, Cuv. Body long, contractile, cylindrical, divided by wrinkles into a great number of apparent rings. Mouth without teeth, subterminal, bilabiate, the upper lip larger than the other, advanced. No eyes.

This genus corresponds to Enterion of Savigny, and contains the earth-worm and other species. The setae are rough and short, as if unguiculated. Each segment is provided with eight of these setae, that is, four on each side, united in pairs, and forming, by their distribution on the body, eight longitudinal rows, of which four are lateral and four inferior. From six to nine of the segments, comprised between the 26th and the 37th, are swollen, and form towards the anterior and superior portion of the body a kind of cincture, especially perceptible during the breeding season. In the interior of these creatures we perceive a straight wrinkled intestine, unprovided with a caecum, but receiving in its course several muscular fibres (proper to the rings of the body), which form an equal amount of small diaphragms. Some internal whitish glands towards the anterior of the body are regarded as connected with the generative system. The nervous cord consists of a series or infinity of very small ganglia, closely set together. The circulation of the blood among the Lumbrici is by no means difficult to detect. We may perceive arising from the intestinal canal, and from the inner surface of the outer envelope, an infinite number of small veinous vessels, which interlace with a great assemblage of arterial ones. These veins unite in one common trunk, placed longitudinally beneath the belly, and from that trunk proceed five small canals, which ūnite in a single dorsal vessel, which may be regarded as the heart. From the last-mentioned organ small arteries take their origin, and proceed to form a net-work with the veins of the superficies of the body,— thus completing the circulation. Respiration appears to be carried on at the surface of the skin, most likely by means of extremely small internal branchiae.

The appearance of the common earth-worm {Lumbricus terrestris) is too familiar to need description in this place. We shall merely mention, that beneath the sixteenth segment there are two pores, the uses of which are still unknown. The mode of production is likewise still disputed. Μ. Montegre^[32. Mérn. du Mus. t. i. p. 242. ] maintains that the eggs descend between the intestine and the outer envelope, around the rectum, where they hatch, and are speedily protruded in the living state. Μ. Dufour, on the contrary,^[33. Ann. des Sciences Nat. t. v. p. 17, and xiv. p. 216. ] asserts that they lay eggs resembling those of leeches.^[34. This seeming contrariety is easily reconciled by bearing in mind that these creatures are in fact οvο-viviparous, and are sometime» born in the completed state, sometimes still surrounded by an envelope or egg-like covering. ] See Plate CCLXXVI. figs. 7, 8, 9, 10. The ordinary habits of the earth-worm are well known. 'They inhabit moist earth, which they pierce in all directions, and a quantity of which they swallow. They also, however, feed on animal and vegetable remains, and always prefer soil imbued with those substances. They seek each other’s society chiefly during the night, and in the month of June. Under the specific name of terrestris, naturalists have no doubt confounded many different kinds. Savigny, to whom we owe so much in relation to the Annelides in general, has, since the publication of his great work on that class, devoted his attention more particularly to the genus Lumbricus, and has ascertained the existence of about twenty-two species in the environs of Paris alone.^[35. See also Μ. Morren’s Treatise Ds Lumbrici terrestris Historia Naturali nec non anatomica. Brux. 1829. ]

In the genus Eypogocon of Savigny, each segment is furnished with an additional seta on its dorsal surface, and the setae are long, spiny, and sharp-pointed. The body in form and colour greatly resembles that of thecommon earthworm, but the segments are less numerous, not exceeding 106, whereas those of the latter amount to 120 and upwards. The only species with which we are acquainted is Hyp- hirtum, first observed in the neighbourhood of Philadelphia.

Genus Nais, Linn. Body elongated, linear, flattened, transparent or semi-transparent, and in general provided with lateral ciliae, simple or in tufts. Segments less distinctly marked than in the earth-worm.

The synonymy of this genus is very confused, its nature and attributes obscure, and its position in the system consequently various, according to the views of different observers. The name, borrowed from the heathen mythology, was first applied by Muller, and was generally adopted by contemporaneous, as it has been by succeeding, naturalists. It was written Naias by Bruguieres∙(in Encye. Method.'), an erroneous alteration, in so far as the latter term had been previously consecrated by Linnaeus to a genus in botany. Lamouroux increased the confusion by bestowing the name of Naisa on a polypus genus of the family of Tubularia, already known by the title of Plumas-tella ; and the resemblance of the two names has induced some compilers to refer to them as synonymous, although they in fact signify objects belonging to separate classes of -the animal kingdom.

Lamarck and Cuvier, in preserving the name of Nais to the subjects of our present notice, do not agree regarding their relations to other groups. The former author places them in the third or concluding order of his class Vermes ( Vers hispides), thus disposing them between the genus Gordius and the Epizoariae. His reason for so doing is, that the structure of the Naides is by no means sufficiently composite to entitle them to a place among the true Annelides; and the fact of their being capable of multiplication by incision, shows that their nature is somewhat anomalous in relation to the last-named class. We may bear in mind, however, that notwithstanding the observations of Trembley and Roesel, their tomiparous generation is doubted by Bose; and, all things considered, we regard them as more nearly related to the genera Nereis and Lumbricus than to any other. We therefore follow Cuvier in placing them among the Annelides.

The Naides in general are small vermiform creatures, of a few lines in length, of a reddish colour, though diaphanous, extremely active in their movements, and of a voracious disposition. They abound in fresh waters, where some dwell upon aquatic plants,—others beneath stones, or in ’perforations in the mud. They prey on minute Crustacea, such as the genus Daphnia, and on the still minuter animalcular tribes, and are themselves greedily devoured [7:11:223]by the fresh-water polypi, which swallow them up, notwithstanding the pointed ciliae with which their sides are armed. These ciliae, however, and other apparently indigestible portions, are afterwards disgorged by the polyp;, in the same manner as owls and other birds of prey reject from their stomachs little rounded pellets of hair and feathers.

The productive powers of the Naides, by whatever process accomplished, are truly astonishing. They appear in countless thousands in the waters of marshes after the lapse of a few hours, prior to which only some solitary individuals were perceptible. The mouth in these animals is sometimes a simple cleft, sometimes an opening, accompanied by two lips. The N. proboscidia of Gmelin, being provided with a trunk, forms the genus Stylaria of Lamarck; while certain anomalous species; such as Lumbricus tubi~ fex and marinus of Muller, constitute the conterminous genus Tubifex of the former author. They dwell in perforations in the mud of streams and marshes, and in the sand of the sea-shore. We may conclude by observing, that the nervous system of the Naides is unknown, and that the ocular points on the heads of certain species, though vaguely named eyes, cannot with any certainty be regarded as organs of vision.

Genus Climena, Lam. Head without tentacula or other appendages. Body cylindrical, composed of few segments, somewhat swollen about the middle, and attenuated at either end. The posterior extremity is truncated and radiated.

These creatures inhabit fixed tubes of a cylindrical form and membranous texture, open at both ends. Our illustration, Plate CCLXXVI. fig. 6, represents Cl. am-ρhistorna, a species taken in the Gulf of Suez, and indigenous to the shores of the Red Sea. Its tube is composed exteriorly of grains of sand and fragments of shells, and is usually attached to the interstices of rocks, or to Madrepores and other productions of the sea.

FAMILY II.—ABRANCHIA ASETIGERA.

This family comprehends such of the abranchial order as are unprovided with setae, and is constituted by the old genera Gordius and Hirudo of Linn., of which all the distinctly-known species are aquatic.^[36. AVe do not exactly know what species of the lower tribes is alluded to by Sir T. S. Raffles in one of his letters descriptive of an excursion from Bencoolen. “I must not omit to tell you, that in passing through the forest, we were, much to our inconvenience, greatly annoyed by leeches ; they got into our boots and shoes, which became filled with blood. At night, too, they fell off the leaves that sheltered us from the weather, and on awaking in the morning we found ourselves bleeding profusely. These were a species of intruders we were not prepared for.” Another species of land leech is said to inhabit Madagascar, where it occurs on plants.· It seizes greedily on the legs of the passers by, and sucks their blood. ]

The leeches in general (Hirudines) are characterized by an oblong body, sometimes depressed, transversely wrinkled, and furnished with a dilatable cavity at either extremity—that is, the mouth is surrounded by a lip, and the posterior end is provided with a flattened disk. These latter parts are useful as organs of prehension and locomotion, and also act as suckers. The mouth, placed in the anterior cavity, is furnished with three jaws.

These useful vermes were probably known in very ancient times. The Halucah or Gnaluha of the Hebrews appears to have been one of this tribe, at least the term has been so translated in our versions of the Proverbs, ch. XXX. V. 15. “The horse-leech hath two daughters, crying, Give, give.” The Greek writers make mention of them under the name of Bdella, and the Latin authors under those of lnrudo and Sanguisuga ; but the ascertainment of the precise species indicated is by no means easy. After the revival of learning we have various general no tices of their history and habits, although it was so late as the time of Linnaeus before we attained to any knowledge of their specific distinctions. The Swedish naturalist (in his Fauna Suecica) described eight species, and numerous additions have been made in more recent times. For a long period the genus Hirudo, as founded by Ray and adopted by Linnaeus, experienced no subdivision; but the labours of Leach, Oken, Savigny, Lamarck, and others, have shown the propriety of re-arranging a group, consisting no doubt of natural constituent parts, but composed of beings exhibiting a varied range of structure, and too much extended for the formation of a genus, properly so called.

The structure of these creatures is soft and contractile, composed of a great number of articulations, and generally invested by an abundant supply of mucous moisture. The anterior cavity, which contains themouth, is named capula by Savigny, while the posterior disk bears the name of cotyla in the nomenclature of that author. On the anterior segments certain small black points are observable, which some designate as eyes, but which have scarcely been proved to fulfil the functions of those organs. They vary in number in the different genera, from two to ten. Various experiments have been made with a view to the ascertainment of this sense. If we place leeches in a vessel surrounded by black paper, and permit the light to enter only by means of a single small orifice, they are by no means slow in directing themselves to that point ;—but this observation we deem to be in no way conclusive, in as far as light produces an efficient action and a directing influence, not only upon many of the lowest tribes, which we know to be destitute of eyes, but even upon the subjects of the vegetable kingdom. Μ. Moquin-Tandon however asserts, that having placed a small piece of red-coloured wood in front of Nephelis vulgaris, it evidently turned round on purpose to avoid it.^[37. Monographie de la famille des Hirudinées. Montpellier, 1826, in 4 to. ] Their perception of the sense of touch is delicate, although they possess no special or circumscribed organs for its reception. The sense of taste is obvious,—that of hearing and of smell imperceptible. No odour affects them,—no sound seems to produce any influence; nor can we detect any organs which may reasonably be deemed the seat of these last-named functions.

The tegumentary system of leeches has been examined in detail in very few species. In the medicinal leech three parts are, however, distinguishable—the epidermis, an intermediate layer which is the seat of colour,—and the dermis. The epidermis is extremely fine and delicate, perfectly colourless, and remarkably deciduous, that is to say, it is frequently renewed, even as often as once in every four or five days in warm weather. It adheres intimately to the lower layer, but not by its entire extent—being frequently free between the rings of which the body of the creature is composed. When detached we perceive that it is perfectly transparent at the points which adhered to the coloured layer, and slightly opake, or even of a whitish colour, where it became unattached in passing from one segment to another. Under the microscope it is seen to be pierced by an infinity of small holes, through which a mucous liquid flows, which lubricates the surface. The coloured layer, or pigmentum, adheres strongly to the dermis on which it lies. The hues which it exhibits are very different according to the species,—sometimes they are [7:11:224] dark and uniform, but usually lighter on the under than the upper surface; sometimes the ground colour is varied by spots or streaks of different intensities, while the pigment, if we may so express it, is occasionally almost colourless, and we may then perceive distinctly through the skin all the interior organs of the body. The dermis, or deepest layer, exhibits a curious organisation; it consists of a thickish tunic, presenting an appearance of distinct circular articulations, which produce the ringed or wrinkled aspect of the external surface. The spaces which exist between these rings are covered by the epidermis, and seem intended to facilitate the varied movements of the animal.

Beneath the skin, of course, are placed the muscles. We find first a layer of transverse fibres, which adheres intimately to the dermis. This layer covers other muscles, of which the direction is longitudinal; and beneath these we find some more, of which the direction is again transversal.

The capula or oral sucker is formed by two extensile lips; the one superior, usually large, sometimes almost lanceolate—the other inferior, and less advanced. Within it are placed the jaws, rarely wanting, and usually three in number, disposed triangularly, and fixed upon a corresponding number of little tubercles. Their consistence is slightly cartilaginous, their form almost lenticular, and their margin, free and cutting, is sometimes smooth, sometimes furnished with a double row of dentations, more or less numerous according to the different kinds. A sort of cartilaginous ring, which frequently surrounds the base of the tubercles, indicates the opening of the intestinal canal, which commences by a species of oesophagus more or less narrow, presenting occasionally some longitudinal folds, but never any lateral pouch-like swellings. The ensuing portion or stomach, on the contrary, usually exhibits throughout its entire extent expansions more or less perceptible, according to the state of repletion. In certain species (such as Clepsina complanata) these lateral appendages are never effaced, but constitute permanent caeca. The rectum is generally separated from the stomach by a valvular contraction. The anal opening is on the back, at the origin of the posterior sucker, called cotyla by Savigny. The digestive canal is throughout composed of two pellucid tunics, and towards its extremity some muscular fibres are perceptible. Although the existence of a liver in the leech tribe is not so ascertained as to be at all generally admitted (indeed it is denied by some, and doubted by many), yet Μ. Blainville describes an apparatus for the secretion of bile, consisting of a cellulo-membranous tissue, surrounding a portion of the stomach and intestine.^[38. Essai d’une Monographie de la famille des Hirudinées. Paris, 1827, in 8vo. ]

All leeches are blood-thirsty and voracious, and support themselves by sucking the life-blood of other animals. Their powers of digestion and assimilation are, however, extremely slow. After the lapse of days, weeks, and even months, portions of the liquid or solid matters which they may have Swallowed are found to remain in the intestinal canal. The kinds used in medicine, moreover, offer this peculiarity, that the blood which they have sucked does not seem to experience any sensible alteration in their stomach, but maintains its natural colour and fluidity. If, however, the leech dies, or the blood is exposed to the air, it speedily coagulates, and becomes of a blackish brown.

The nervous system of the leech tribe has been described in some detail by several authors, especially that of Sanguisuga officinalis, Hoemopis vorax, Nephelis gigas, and Albione muricata. It is composed of a series of ganglions, extending from the mouth to the extremity of the body, and placed, as among the other articulated classes, beneath the alimentary canal. From each ganglion proceed nervous threads, which ramify ad infinitum to the other parts.

The circulating system of leeches has been the subject of still more numerous researches. MM. Thomas,^[39. Mém. pour servir à l’ Histoire Nat. des Sangsues. Paris, 180G. ] Cuvier, Carena,^[40. Monographie du Genre Hirudo, in Mém. de l’Acad. de Turin, tom. xxv. ] Moquin-Tandon, Dugés,^[41. Recherches sur la Circulation, $c. des Annelides Abranches, 1828. ] and Audouin,^[42. Articles Sangsue and Sangsues, in the Diction aire Classique d’Hist. Nat. ] have greatly signalised themselves in that laborious field. All the species hitherto examined have presented four longitudinal vascular trunks,—one dorsal, another ventral (these two being separated by the alimentary canaD, and two lateral. These principal organs communicate with each other, not only by the capillary vessels which meet and intermingle in the different parts to which they are distributed, but also by special branches of considerable diameter, which proceed directly from one vascular trunk to another. The ventral vessel furnishes large branches, which, mounting vertically on either side, embrace the intestinal canal, and open on the dorsal vessel. Dugés names these the abdomino-dorsal branches. The lateral branches communicate with each other by means of transverse branches, which pass beneath the medullary cord. These branches have been lately figured and described by Jean Muller (in Archiv, fur Anat. und Phys.Jsm. Marz. 1828), and Dugés names them latero-abdominal branches. Lastly, these lateral trunks also send large branches to the dorsal vessel, which bear the designation of latero-dorsal branches. In addition to these canals, which thus establish a direct connection between the principal trιmks, each of the latter gives rise to an infinite number of small vessels, which carry the blood to the various parts, and especially to the skin, which may be regarded as the principal, though not the sole, organ of respiration. That other organ, to which we now allude, consists of certain pouches, amply provided with blood-vessels, which form a net-work on their coats, and proceed from the subdivision of a vessel furnished by the latero-abdominal branches, as well as of a large vascular pouch or bag called pulmonary by Dugés, and which is derived from the lateral trunk. In a species of Albione dissected by Μ. Audouin, the lateral vessels were perceived to be in direct communication with the respiratory pouches, by means of two branches, one of which is anterior, the other posterior. He also observed that numerous branches sprang from the anterior portion of the dorsal vessel, and proceeded partly to the pouches, and partly to the lateral trunks. Thus the pouches communicate at the same time, both with the dorsal and lateral vessels. In accordance with these views, the process of circulation is supposed to be as follows. The lateral trunks are regarded as great veins, which receive the blood from all parts of the body, and transmit it to the respiratory pouches, in which it becomes re-oxygenated; a small portion then flows back to the lateral vessels, while the greater portion enters the dorsal vessel, and then the ventral one, both of which assist in propelling it to all the other parts of the body, from whence it returns to the lateral branches, and thence flows to the respiratory pouches as aforesaid. We must add, however, that Μ. de Blain ville and others deny that the pouches or vesicular sacks just mentioned are of a pulmonary nature.^[43. Cuvier seems to express no very decided opinion on the subject above referred to. “On voit dans plusieurs en dessous du corps deux séries de pores, orifices d’autant de petites poches intérieures que quelques naturalistes regardent comme des organes du respiration bien qu’ils soient la plupart du temps remplis d’un fluide muqueux.” (Règne Animal, t. iii. p. 213.) ] They regard them [7:11:225]rather as secreting glands, and it is certain that respiration is carried on in great part through the medium of the skin. Various kinds of leeches may be often seen fixed by their posterior sucker, and swinging themselves to and fro for hours and even days together, their bodies being at that time more than usually flattened, in order to render the motion more effective. They are then respiring after the manner of the Naids, by bringing their cutaneous system into constant contact with a fresh supply of water. During this singular process the pulmonary pouches are almost quite inert, and their sanguineous vessels scarcely perceptible, while the cutaneous net-work, on the contrary, is in full and remarkable activity.

Leeches are hermaphrodites, like others of their class; but sexual union of separate individuals is indispensable to the process of fecundation. Although in many of their more obvious characters they so nearly resemble the Planariae„they stand too high in the scale to be capable of reproduction by excision, or the cutting of parts. A variety of opinion exists among naturalists regarding the mode of production, whether by eggs or living young. It is probable that such as do not appear to lay eggs are merely ovoviviparous, and bring forth their young alive, after they have been hatched in the body of the parent. The majority of species in truth lay oviferous capsules, each containing several germs. Certain kinds of Clepsina are distinguished by this peculiarity; a small pouch exists in the abdomen, in which the young seek protection during infancy. They attain to full size rather slowly, and the duration of life is considerable, though not distinctly known. Medicinal leeches have been kept in life for a period of eight years; and it has been inferred, that if, with the disadvantages of confinement, and irregular supplies of food, they survive so long, their natural term of life must be much greater. This, however, we regard as an inconclusive, if not erroneous mode of reasoning; for we know that among insects and other classes of the more lowly organized departments of animal life, abstinence, and the non-fulfilment of their natural instincts, are uniformly found to prolong their period of existence.

The leech tribe in general is widely distributed over the earth’s surface, although, as usual, each species has its own range of localities.^[44. We observe it stated in several continental works of authority, that leeches are unknown in, or at least not indigenous to, the western world. We were inclined α priori to doubt the accuracy of this statement, ami lately instituted some inquiries on the subject, in which we were aided by an excellent physiological naturalist of this city, Dr Alien Thomson. We find that in the Dispensatory of the United States, by Drs Wood and Bache (published at Philadelphia in 1833), there is a description of a true American medicinal leech. These authors state, that at New York, Boston, and elsewhere, European leeches, that is, the gray and green varieties of the Hirudo medicinalis of Linnaeus, are chiefly employed, and are imported in great quantities; but that in Philadelphia and the neighbourhood the indigenous Hirudo decora is used. It is this species which is described in Major Long’s Second Expedition (vol. ii. p. 268). The back is of a deep pistachio-green colour, with three longitudinal rows of square spots, twenty-two in number, and placed on every fifth ring. The abdomen is spotted with black. This kind usually measures two or three inches in length, occasionally attaining to the extent of four or five inches. It is carried to Philadelphia by the country people from Bucks and Berks county. It is said to draw less blood than the European leech, and does not cut so deeply. About three American do not more than correspond to a single European leech in their suctorial powers. ] Our medicinal kinds seem proper to Europe, although they extend from Russia to the southern point of Spain. All the species are extremely sensible of atmospheric changes. They seem agitated during high winds, and often bury themselves in the mud during cloudy weather. Some fanciful observers have even kept them in confinement, that they might serve to indicate the weather; but we incline to think that it is fully as useful, and not more troublesome, to look out of a window than into a phial. On the approach of cold weather they sink into the mud, and pass the winter in a state of lethargy.

We shall now proceed to a brief consideration of the principal genera into which the tribe has been partitioned by modern naturalists.

Genus Sanguisuga, Sav. Oral sucker consisting of several segments; upper lip almost lanceolate; aperture transversal, jaws three in number, compressed, and each armed on their cutting edges with two ranges of fine teeth. Ten black points (which some regard as eyes) disposed in a curved line; the posterior four more isolate. Anal sucker obliquely terminal.

This genus contains the leeches properly so called, that is, the medicinal kinds; and, according to Savigny, consists of three species. Some recent additions, however, have been made to these by MM. Moquin-Tandon and Carena.

H. medicinalis of naturalists (Plate CCLXXVI.fig. 14) is the most common kind, and that most frequently used for blood-letting purposes. It occurs throughout the freshwater marshes of Europe, and measures from four to five inches in what may be called its medium state, although capable of both contraction and extension within and beyond those limits. Its body, including the anterior sucker, is composed of ninety-eight rings, and is of a deep-green colour on the back, with six reddish bands, three on each side. The two inner bands are almost spotless; the two central ones are marked by a chain of small spots and points of velvet-black; the exterior bands are marginal, and each subdivided by a black fillet. The abdomen is of an olive colour, broadly bordered and spotted with black. Savigny distinguishes, under the name of *9. officinalis (it is the H. provincialis of Carena), another species, likewise used in medicine (see Plate CCLXXVI. figs. 11 and 12), and frequently confounded with the preceding. It is vulgarly known as the green leech, and resembles the common kind in size, and the number of its segments; but the colour of the back is not so sombre, and the abdomen is of a more yellow green, and, though bordered with black, is without spots. The six anterior eyes are very projecting, and have more truly the appearance of organs or vision. The third species mentioned by Savigny is the >9. granulosa. It was brought by Μ. Leschenhault from Pondicherry, where it is used in blood-letting after the manner of our European kinds. <9. obscura and interrupta are both described by Μ. Moquin-Tandon as indigenous to the vicinity of Montpellier; and S. verbena of Carena occurs in the Lago Maggiore.

With the exception of the last-named species, and that from Pondicherry, Μ. Blainville refers all the others to the H. medicinalis of Linn., of which, according to his peculiar views, he establishes five varieties; the grey, the green, the spotted, the black, and the flesh-coloured. With that love of change for which too many modern naturalists are remarkable, he names the genus Jatrobdella.

We have already mentioned that leeches are abundant in all the countries of Europe. France furnishes an immense supply, and their collection in some of her provinces affords the materials of an important branch of commerce. Some curious details on the subject were read several years ago to the agricultural society of the department of Seine-et-Oise. Towards the month of April or May, according to the nature of the season, the country people collect the cocoons or capsules formerly mentioned as containing the eggs. These they find in abundance in the mud of shallow marshes, and convey them [7:11:226]to various reservoirs in other quarters, so as to spread and propagate the breed. They do not use them commercially till they are about eighteen months old. Leeches are very numerous in the lakes and marshes in the neighbourhood of Nantes; and their collection is carried on throughout the whole year, but chiefly during summer. They are transported to Paris in linen bags, each containing about 500, placed in panniers, and surrounded by wet moss. During a favourable season the dealers of Nantes will sometimes receive at the rate of fifty thousand every day; and a Parisian druggist informed Μ. Audouin, that in the summer of 1820 he received from Moulins 130,000 for his own share.^[45. Diet. Class. d’Hist. Nat. t. xv. p. 108. ] Many leeches refuse to bite. This generally arises either from their appetite for food having been recently satisfied, or from their being about to change their skins. It is believed, however, that capricious individuals sometimes occur, which will not suck at all; and of this it is impossible to ascertain the cause. Inflammation occasionally follows the infliction of the bite, and in this case a vulgar prejudice exists that a horseleech has been applied. This is in every way an error, for the horse-leech refuses to fasten upon the human body. The means used for the preservation of leeches in confinement are various. The most common mode consists in placing them in a bottle of water frequently renewed. Some apothecaries find advantage from placing moss or aquatic plants at the bottom of the vessel, which aid in freeing them from slime. The chief dispenser of the marine hospital of Rochefort keeps his leeches simply in moistened clay, in which the creatures form holes and galleries, where they live happily for years.

Genus Haemopis, Sav. Differs from the preceding chiefly in the jaws being not compressed, and furnished with less numerous dentations. (Plate ĊCLXXVI. fig. 15.)

H. sanguisorha, Sav. {Hirudo sanguisuga, Linn.), commonly called the horse-leech, is a well-known species, somewhat larger than the medicinal kinds, and of a uniform greenish-black colour. A great diversity of opinion seems to exist regarding the blood-drawing propensities of this species. Many allege that it causes wounds extremely dangerous both to man and beast. Linnaeus asserts that nine will kill a horse. MM. Huzard and Pelletier, on the other hand, maintain that the horseleech, improperly so called, never attacks any vertebrated animal whatever;^[46. Journal de Pharmacie, Mars 1825. ] while Μ. de Blainville again is of opinion that these writers have mistaken their subject of observation, and have described the black leech (his Pseudobdeila nigra), which is truly characterized by the jaws being nothing more than folds of toothless skin, and may therefore be inferred to confine its attacks to the lower orders of creation. We agree with Cuvier in thinking that the subject deserves a fresh examination. In addition to the common species, Savigny describes three other kinds, H. nigra, luctuosa, and lacertina. Genus Bdella, ^[47. Though we adopt the above name, we beg to protest against its propriety of application, in as far as it had been previously used to designate a genus of the class Arachnides. ] Sav. Dentations of the jaws entirely wanting. (Plate CCLXXVI. fig. 17.) Eyes only eight in number.

As far as we know, this genus consists of only a single species, the Bd. Nilotica, found in Egypt, and familiar to the Arabs under the name of Alak. It appears to have been known to the ancients; and Herodotus (Hist, lib. ii. cap. 68) describes it as a parasite of the crocodile. It is of chestnut-brown colour above, of a lively red below. (Plate ' CCLXXVI. fig. 16.)

Genus Nephelis, Sav. In this genus the eyes are also only eight in number, the four anterior being disposed in a crescent form, the four posterior ranged on each side oh a transverse line. The jaws are reduced to three simple folds.

Savigny describes three species, N. rutila, testacea, and cincrea. The two former occur near Paris; the last named is frequent in the marshes of the forest of Fontainebleau.

The genus Trochetia of Dutrochet^[48. The title of this genus, it we mistake not, is liable to an objection similar to that stated in the preceding note,—Decandolle having previously established Trochetia as a genus in Botany. (See Mím. du Museum, t. x. p. 106.) ] does not seem to differ from the preceding, except by an enlargement near the position of the generative system. One species (Geob-della trochetii of Blainville) comes on shore in pursuit of earth-worms. Another minor genus has been established by Μ. Moquin-Tandon, under the name of Aulastoma. The jaws are represented by numerous projecting folds. The eyes are ten in number. We may here also mention Μ. Odier’s genus Branchiobdella, of which the jaws are two in number, and the eyes wanting.^[49. We have already explained under what reservation of doubtful function we use the word eyes, in reference to the tribe of leeches. ] It inhabits the gills of cray-fish.^[50. Mím. de la Soc. d’Hist. Nat. t. i. pl. iv. ]

In all the preceding groups or genera of leeches, the anterior sucker is but slightly distinguishable from the adjoining portion of the body; but in the two following genera it is rendered more perceptible by a restriction, and is composed of only a single segment. In the genus Haemocharis of Savigny, the eyes are eight in number, the body slender, and indistinctly ringed. The species do not swim, but march after the manner of the surveyors or geometric caterpillars. They attach themselves particularly to fishes. The genus Albione of the same author differs from the preceding in its body being beset by tubercles, and in possessing only six eyes. The species inhabit the sea. We may mention as an example the Hirudo muricata of Linn.

The genus Branchellion of Sav. is distinguished by what some regard as projecting branchiae. The epidermis is loose and ample, and seems to enclose the animal as in a sack. The species are parasitical, and attach themselves chiefly to fish of the torpedo kind. With the leeches, Cuvier also places the genus Clepsīna, Sav., which is characterized by a broadened body, possessing only a posterior sucker. The anterior portion is a simple orifice, without any appearance of the usual disk. (See Plate CCLXXVI. figs. 13 and 13 α .) The species make a near approach to the Planar-ice, and the one represented by the figure just referred, to was described and figured by Mr Kirby, under the name of Hirudo crenata. ^[51. Linn. Trans, ii. tab. 29, p. 318. ] Other genera, allied to the preceding in their enlarged form and absence of the oral disk, have been established by Oken and Blainville. Of these, however, we cannot give account within our prescribed limits, and we shall therefore conclude the present treatise by a short notice of the more distantly related.

Genus Gordius, Linn. Body filiform, smooth, or with very slight transverse markings. Neither branchiae nor tentacula of any kind.

A well-known species of this genus (G. aquaticus, Linn.) is distinguished in this country by the name of the haircel. It occurs in springs and marshes, and among moist [7:11:227]sand. It also dwells in mud, which it perforates in all directions. The position of the genus is variously regarded by different naturalists, and the extreme tenuity of form in these creatures has probably opposed obstacles in the way of a precise knowledge of their structure. The nervous system being composed of a ganglionic cord, seems, however, a strong reason for placing them among the Annelides. We follow the Baron Cuvier in so doing, although we are aware that Rudolphi and Blainville combine them with the genus Filaria, which contains the noted Guinea worm (F. Medinensis), and is usually regarded as belonging to the intestinal class.^[52. A common belief prevails in this country among the young and ignorant, that Gordii or hair-eels derive their origin from horsehairs, or at least, that if a hair plucked from the tail of a horse (or probably a mare) is placed in water, it will ere long assume the form and fulfil the functions of a Gordius,—in other words, will become animated. We once heard this subject very gravely discussed in a company of poets and philosophers. The writer of the preceding sketch maintained, perhaps more seriously than so absurd a subject deserved, that such a transformation coulΛ not le. His arguments, which proceeded on certain general principles not necessary to be here narrated, were met by an equally serious assertion on the part of an ingenious and well-known pastoral poet, an honoured native of the vale of Ettrick, in the south of Scotland, that he had not only seen the conversion of a horse-hair to a hair-eel, but that having on one occasion, while engaged in angling, dropped a fishing-line from his hat-band, he had the good fortune to recover it some weeks after in the form of a congeries, all twisted and entwined together, of hair-eels! !! What became of the hooks? thessed be the day I ’scaped the Stygian crew, From Pyrrho’s maze, and Epicurus’ sty, And held high converse with the godlike few, Who to the enraptured heart, and ear, and eye, Teach virtue, beauty, love, and truth, and melody. ] (τ.)

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