purposes principally, and are generally confined to the gardens of cottages or farm-houses, where the quantity of produce is more valued than its quality. Much the finest variety of this sort of plum is that called the Shropshire Damson, which is extensively multiplied in the nurseries by grafting. [PLUM, in ARTS AND SC. DIV.] DANEACEÆ, Danaworts, a small natural order of Plants related to the Ferns. They have all the habit of Dorsiferous Ferns, but their spore-cases are ringless and combined in masses, splitting irregularly by a central cleft. The species are all tropical. It embraces the following genera :-Kaulfussia, Angiopteris, Danæa, Eupodium, Marattia, and about fifteen species. Angiopteris evecta is said to be employed in the Sandwich Islands to perfume cocoa-nut oil. The rhizome of a species of Marattia is eaten by the Sandwich Islanders.

DANBURITE, an American Mineral. It occurs crystallised. Its primary form is an oblique rhombic prism. The colour honey-yellow, becoming nearly white by decomposition; streak white. Hardness 7.5. Lustre vitreous; translucent, transparent. Specific gravity 2.83. It is found at Danbury, Connecticut. The following is the result of an analysis by Shepard :—

DAPE'DIUM, changed by Agassiz to Dapedius, one of the first described British genera of Fossil Ganoid Fishes. To D. politum of De la Beche (Geol. Trans.,' 2nd series, vol i. pl. vi.) six others are added by Agassiz, all from the Lias.

DAPHNE, a genus of Plants belonging to the natural order Thymelacea, containing many species, inhabiting the more temperate parts of Europe and Asia. Among them some are cultivated in gardens for their beauty or fragrance, others are of medicinal importance, and a few are employed in the manufacture of hemp and paper. We shall briefly notice the more remarkable of these.

The genus Daphne is distinguished in its natural order by having 8 or 10 stamens inclosed within the calyx, a simple stigma, a succulent fruit, and a calyx, the orifice of whose tube is destitute of appendages.

D. Mezereum, the Mezereon of the gardens, is a deciduous plant, with white or purple fragrant flowers, sitting close to the stem, and appearing on the naked branches before the leaves are unfolded. It is a favourite in gardens, and succeeds in almost any well-drained light soil where the air is not poisoned by the smoke of coal-fires. It is found wild in the mountainous woods of many parts of the middle and south of Europe. It is met with in woods in various counties of England. The berries are smooth, shining, and bright red.

All the parts of this and indeed of the other species, as far as they have been examined, are extremely acrid and poisonous. If the bark is bruised and applied to the skin, it produces severe blisters, and is sometimes substituted for cantharides when that drug cannot be employed with safety. Taken internally, the bark, leaves, and fruit, act as cathartics, but require to be administered with extreme caution; for they are apt to produce dangerous and even fatal consequences. Linnæus speaks of a person having been killed by a dozen Mezereon berries; and they are employed in Sweden to poison wild animals. According to Fée, the very odour of Daphne, agreeable as it is, is attended with danger; he says that if kept in sittingrooms they will bring on headache and fainting. It is moreover asserted that Russian and Tartarian women sometimes rub the berries of the Mezereon on their cheeks to produce a slight irritation, which of course gives the effect of rouge, only in a more permanent degree. (MEZEREON, in ARTS AND SC. DIV.)

D. Laureola, the Spurge Laurel, is another British species, found wild commonly in woods and hedges. It is a handsome evergreen bush, with the aspect of a laurel. The leaves are placed very close together; they are of a leathery consistence, deep green, lanceolate, acute, and narrowed to the base. The flowers are green, and grow in little short clusters, which are nearly concealed by the leaves. The berries are, when ripe, a deep purple black. We have no species that grows more readily beneath the shade of trees; and as its appearance is highly ornamental, it would be a most useful garden plant, if it were not for the dangerous berries, which children are apt to eat. An ointment for keeping blisters open is prepared from this plant. D. pontica. One of the plants which is reputed to have contributed to the poisonous quality of the honey that was eaten by Xenophon's soldiers, is very like this species, and is often cultivated as a hardy

evergreen.

D. Gnidium, the Garou-Bush, an evergreen with narrow sharppointed erect light-green leaves, and branching clusters of white fragrant flowers, is a common plant in dry waste places in the south of Europe. It will not live in the open air in England, except in the

warmest counties. Both the berries and leaves are employed by the French as purgatives. The plant also affords a good yellow dye. D. Cneorum, a native of grassy places in the Alps of Switzerland and the rest of Central Europe, with its trailing stems, numerous small narrow blunt deep-green leaves, and clusters of rich purple fragrant flowers, is one of the most beautiful of all plants, when it finds a soil and climate that suit it. At Bagshot, for instance, and in similar situations, it is under good management quite unrivalled by the other hardy shrubs among which it grows. It will not succeed where the soil is otherwise than sandy and peaty, nor can it bear the impure atmosphere of large towns.

D. collina, D. alpina, D. Neapolitana, and D. Tarton-raira are other species cultivated in gardens. The first has dull purple sweet-scented flowers, and is sufficiently common in collections; the others are rarer. All are impatient of wet in winter; but if at that season kept tolerably dry will bear considerable frost, and are desirable garden plants in the milder parts of England.

In addition to the acrid and dangerous properties which appear to be common to them all, some species are remarkable for the toughness of their fibre, and for the economical purposes to which they are applied. From D. Cannabina is prepared the best kind of writing. paper in China, according to Loureiro; but it must be observed that this statement, if true, is at variance with what is observed in Nepaul, where the daphne-paper is very brittle and bad.

D. Lagetta, the Lace-Bark-Tree of Jamaica, is most remarkable for the tenacity of the fibre of which its bark consists, and for the facility with which it may first be separated into thin layers and then into distinct meshes. If the inner bark of this plant be macerated in water it may be readily separated into layers no thicker than the finest lace, and which after having been pulled a little sideways resembles in some measure that fabric. King Charles II. is said to have had a cravat, frill, and ruffles of Lace-Bark presented to him by his governor of Jamaica.

DAPHNIA, a genus of Entomostracous Crustacea, belonging to the division Branchiopoda, the order Cladocera, and is the type of the family Daphniade. This genus is characterised by Baird as follows: Head produced downwards into a more or less prominent beak. Superior antennæ exceedingly small, 1-jointed, and situated under the beak; inferior antennæ large and powerful.

Several other genera have been formed out of the species that were formerly referred to the genus Daphnia. [BRANCHIOPODA.] D. Pulex (Latreille), the Water-Flea, is the best known species of this genus. It is known by a multitude of names, the most common of which is the Water-Flea. The whole of the species however have this designation. The following are some of the synonyms:

This little creature forms a beautiful object for the microscope. Its shell or carapace is transparent, and through it can be seen the whole of its interior organisation. The lower extremity of the valves terminates in a sharp spine, which is serrated at the edges. The head is large; the superior antennæ are very small, whilst the inferior antennæ are very large. The male is much smaller than the female, and is comparatively rarely met with. It is found commonly in ponds and ditches round London at all seasons of the year. It is frequent in the cisterns which supply the houses of London with water.

D. psittacea, Baird. It closely resembles the last species, but Dr. Baird says, upon close examination, "The form of the head and the serrated dorsal margin distinguish it very readily."

D. Schafferi, is a larger species than D. Pulex. It is about the fifth of an inch in length and two lines broad. Their motion through the water is peculiar, being a tumbling wavy sort of movement. They remain at the bottom of the water. They are very much infested with species of Vorticella.

D. retula is common round London, and has a smaller head than D. Pulex. It is the Daphnia sima of Müller and Monoculus simus of Gmelin.

There are three other species noticed by Dr. Baird in his 'British Entomostraca.' D. reticulata, D. rotunda, and D. mucronata. The last is a rare species.

(Baird, Natural History of British Entomostraca.)
DA'PSUS, a genus of Coleopterous Insects. [EUMORPHUS.]
DAPTRIUS. [FALCONIDE.]

DA'PTUS (Fischer), a genus of Coleopterous Insects belonging to the family Harpalida. It has the following characters:-Mentum deeply emarginated and without any tooth-like process in the middle; antennæ rather short, and moniliform; second joint of the labial palpi somewhat oval; four basal joints of the four anterior tarsi slightly dilated, short, and triangular; body more or less elongated, the elytra with their outer margins almost parallel.

D. vittatus is of a pale yellowish colour, with an oblong black spot on each elytron; the head and thorax are more or less clouded with brown or black in some specimens.

This species is about a quarter of an inch in length, and inhabits

DASYORNIS. [MERULIDE.] DASYPROCTA. [AGOUTI.] DASYPUS. [ARMADILLO.] DASYURUS. [MARSUPIATA.] DATE-PALM. [PHOENIX.]

DATHOLITE, a Mineral which contains Boracic Acid, Silica, and Lime. It has been found at Arendahl in Norway, and a few other places. It occurs both massive and crystallised in rhombic prisms, the lateral edges and the solid angles of which are usually replaced by planes. The colour of Datholite is grayish or greenish white, and it is translucent. Its specific gravity is about 3. It yields to the knife. The fracture is imperfect conchoidal. The lustre is somewhat vitreous. According to the analysis of Vauquelin, it consists Boracic Acid

of

Silica Lime Water

21.67

37.66

34.

5.5 98.83

DATISCA'CEE, Datiscads, a small natural order of Plants allied to Begoniaceae and Cucurbitaceae, and the other apetalous orders in their vicinity, but distinguished by its inferior ovary with parietal placenta. It has unisexual flowers; the males have a calyx of several pieces, and from 8 to 15 stamens; the females have an obsolete superior calyx, and three little recurved stigmas at the apex of an oblong 1-celled ovary, with 3 many-seeded parietal placenta. The seed-vessel opens at the end like that of Reseda; the seeds are

A male plant of Datisca Cannabina; A, a cluster of ripe fruit from a female plant.

inclosed in a finely netted bag, and contain a straight embryo without albumen. The order has 3 genera and 4 species. Datisca Cannabina, the commonest plant of the order, is an herbaceous dioecious perennial, with stems about 3 feet high, pinnated leaves with from 5 to 9 ovate-acuminate coarsely-serrated leaflets, and long racemes of flowers collected in clusters in the axils of long linear bracts. It is a native of the southern parts of Europe, where, especially in Candia, it is used on account of its bitter tonic properties as a substitute for Peruvian bark; it also affords a yellow dye. DATU'RA, a genus of Solanaceous Plants, with a funnel-shaped angular 5-lobed calyx, a corolla of a similar form, but much larger, and a 4-celled capsule, which is either smooth or muricated externally; the base of the calyx moreover adheres to the seed-vessel in the form of a circular disc.

Several species of this genus are known in cultivation, the very large size of their funnel-shaped flowers rendering them conspicuous objects; they have however a nauseous odour, and are only handsome when in flower, for which reason they are not general favourites. They are all exotics, with the exception of the following, in whose properties they coincide.

D. Stramonium, the Thorn-Apple, is by no means an uncommon annual upon dunghills, rubbish-heaps, and waste-places near houses. It grows about 3 feet high, with a light-green stiff stout stem, which is slightly downy near the upper end. The leaves are broad, oval, stalked, sharp-pointed, sinuous, and angular. The flowers are large, white, or occasionally dull light purple, and grow singly from the side of the stem opposite the origin of the leaves; they are erect, and placed upon a very short peduncle. Their calyx is tubular, elongated, a little swollen at the lower end, with five prominent ribs, ending in as many sharp-pointed lobes; after flowering, it all drops off, except the base, which surrounds the fruit in the form of a circular disc. The corolla is much larger than the calyx, of a similar form, but its lobes are more taper-pointed. There are five stamens, which are inclosed in the tube of the corolla. The ovary is covered with small sharp points, and contains four cells, in each of which is a considerable number of ovules. The style is cylindrical, smooth, and enlarged at the upper end. The fruit is a spiny oval capsule of four imperfect cells, which communicate with each other in pairs. The seeds are brown, kidney-shaped, with a scabrous surface.

This plant is well known, under the name of Stramonium, as a powerful and dangerous narcotic. Its leaves and seeds are the parts employed, and they are found to possess properties similar to those of henbane and belladonna. The leaves are occasionally smoked, especially by country people, as a remedy for asthma; the seeds are employed by thieves to drug the beverage of their victims. In small doses they produce symptoms of frenzy; in larger quantities stupor and death. The poisonous principle of this and other species is considered a peculiar vegetable alkali, and called Daturine. [STRAMONIUM, in ARTS AND Sc. Div.]

D. arborea and D. bicolor, beautiful arborescent South American plants, the former with long white flowers, and the latter with yellow or scarlet ones, are noble objects in the gardens of this country. They participate in the properties of the true Daturas, but they are not now considered to be genuine species, on account of their calyx slitting on one side, and remaining permanent around the base of the fruit. They are stationed in a genus called Brugmansia.

DAUCUS, a genus of Plants belonging to the natural order Umbellifera. It has hispid fruit, of a somewhat compressed ovate or oblong form, the primary ridges filiform and quite bristly, the secondary ridges prominent, winged, and divided at the edge into a number of fine teeth or hooks. De Candolle enumerates 38 species, chiefly biennials, but it is doubtful whether several of them are not mere varieties of each other.

D. Carota, the only one to which general interest attaches, is the Carrot. This plant, which grows wild all over Europe in chalky soil, is believed to be the origin of our garden carrot, but there is no record of its having first begun to change its hard wiry juiceless wild root for the nutritious succulent carrot of the gardens. De Candolle gives for the range of the wild plant the meadows and pastures of Europe, the Crimea, and Caucasus, whence it has been transported into China, Cochin China, America, and elsewhere. [CARROT, in ARTS AND SC. Div.]

D. gummifer is known by having its radical leaves triangular. It is found on the sea-coast of the south of England, and is also called D. maritimus.

DAVILLA, a genus of Plants belonging to the natural order Dilleniacea. It has 5 very unequal sepals, which increase after flowering; from 1 to 6 petals, with linear filaments dilated upwards. The single carpel is testaceous, from 1 to 2-seeded, inclosed in the two inner concave valve-like sepals. The seeds are solitary, enveloped in an arillus, which is only open at the apex.

D. elliptica has a shrubby erect much-branched stem, with hairy branchlets. The leaves are elliptical, obtuse at each end, entire, between crustaceous and leathery, rough and hairless above, downy and netted beneath; the petiole villous on the under side. The racemes are hairy and bracteolate; the sepals silky. The petals from 1 to 6, somewhat obcordate. This plant is an astringent, and furnishes the vulnerary called Sambaibinha in Brazil.

the base on one side a forked branch, on the other a simple one, all of the same thickness. Mr. M'Leay remarks that the organs of digestion have great affinity in external structure and position to those of Cynthia pantex of Savigny, except that the stomach and intestine are horizontal, and the anus simply margined, and that, different as this species is in external appearance from all other Ascidia, internally it agrees with the Pandocia in almost every essential respect but the Ovary. He observes that this singular animal completes the circle of the genus Ascidia in the most beautiful manner. It agrees with the first sub-genus, Cynthia, in the nature of its branchial reticulation and of its digestive apparatus; but Cynthia has two ovaries, the right one contained in the intestinal loop, and the left one coating the tunic. The first of these, or the right ovary, is the only one possessed by Pandocia, and the left is the only one possessed by Dendrodoa. Mr. M'Leay concludes by stating that the distinction between the aberrant groups of Ascidia depends thus upon the nature of their system of generation, as that which exists between the two normal groups depends on their system of respiration.

(Anatomical Observations on the Natural Group of Tunicata, &c., by W. S. M'Leay,; Linn. Trans., vol. xiv.)

DE'NDRODUS, a genus of Placoid Fishes, from the Old RedSandstone of Elgin, Moray, and Russia. Professor Owen has described five species, and Agassiz a sixth.

DE'NDROMUS, a genus of Animals belonging to the order Rodentia, established by Dr. A. Smith in his 'Contributions to the Natural History of South Africa,' with the following characters :

2

3-3

Incisors, Molars, = 16.

3-3

The upper incisors with a longitudinal furrow on their anterior face; the lower long, slender, with the cutting edge cuneated.

The upper first molar with six tubercles in a double row, and two indistinct ones besides, of which one is at the anterior part of the crown of the tooth, the other near another tubercle of the internal series, behind the transverse incisorial lamina; the second molar with two or three longitudinal incisorial lamine by the external margin of the crown, in the middle of which lie three or four obtuse transverse tubercles disposed in a row; the third molar has two transverse incisorial lamine with an interjacent furrow. Below, the first molar has six tubercles disposed in a double series; the second, four obtuse tubercles arranged in the same order; the third is very small, with some transverse laminæ and furrows intermingled. No canines. Rostrum acute. Lip slit. Ears oblong, rather naked, and internally, near the skull, with two transverse membranaceous valvules, of which the lower lies over the external auditory meatus. Tail elongated, annulated, with scattered hairs. Feet divided, ambulatory; the anterior with three toes, and a wart in lieu of hallux; the posterior five-toed: claws falcular.

D. Typus. Above, brown, passing to ferrugineous; beneath, reddish-white; whiskers long, partly black and partly white; upper lip white; ears without and within slightly covered with a fine short reddish-white fur; extremities the same; tail pointed, considerably longer than the body, and of a faint grayish-brown colour; along the centre of the back, particularly towards the tail, an indistinct black line. Length from point of nose to root of tail, 34 inches: length of tail, 44 inches.

It inhabits South Africa, where it is found upon the branches of trees, &c., in which situations it constructs its nest and brings forth its young. Dr. Smith observes that the position of this little animal among the family of mice is not well determined; but that perhaps its place is after the Mouse. ('Zool. Journ.,' vol iv. p. 438.) DENDROMUS. [DUCKS.]

DENDRONESSA. [DUCKS.]

DE'NDROPHIS (Fitzinger), a genus of Serpents placed by Cuvier under the great genus Coluber, and stated by him to be the Aheetulla of Gray. The species of this genus have, like the Dipsas of Laurenti, a line of wider scales along the back, and narrower scales along the flanks, but their head is not larger than their body, which is very alender and elongated. Their muzzle is not elongated, and they are not venomous. They inhabit India and Africa.

DENDROPHYLLIA. [MADREPHYLLICA.] DE'NDROPLEX, a genus of Birds established by Mr. Swainson, and placed by him in the family Certhiada (Creepers), and sub-family Certhiana, which have the tail graduated and rigid.

The bill is very straight. Wings moderate, rounded; third, fourth, and fifth quills longest.

Mr. Swainson observes that he knows not whether the type of this genus has been described, and states that the living bird has all the manner of a Picus. Except in its perfectly straight bill, he adds, it differs not from Dendrocolaptes. (Zool. Journ., vol. iii. p. 354.) DENTA'LIUM, a genus of Gasteropodous Mollusca, whose place in the animal series was first satisfactorily determined by M. Deshayes. Rondelet considered the Dentalia as marine shell-worms (vermisseaux de mer), though he noticed them as worthy of particular attention. Lister introduced them at the end of the Limpets (Patella). Lang followed in nearly the same steps, separating, after the Patella, a section wherein he arranged, together with the Dentalia, all the calcareous tubes of Annelides then known. Breyne placed his genus Tubulus, containing the Dentalia, &c., at the head of his Monotha

NAT. HIST. DIV, VOL. II.

1, Dendrophis Ahætulla, one fourth of the natural size; 1 a, head; 1 b, disposition of the scales above and below the vent. (Iconog.)

lamous Shells, the first of the two grand orders, the Monothalamous and the Polythalamous, into which he divided the Testaceans. In this position Dentalium was separated from the Patella by all the other univalve shells comprised in the Cochlidia, as well as by the Polythalamous series; in short, by the entire interval of the Univalve Testaceans; Breyne, as M. Deshayes observes, having probably considered the Patella as the passage from the univalves to the bivalves, for he places them immediately before the latter. Tournefort gave the Patello a position at the head of the univalve shells, and at the end, before the bivalves, he placed the Dentalia, Entalia, and the other marine testaceous tubes. D'Argenville, in his Zoomorphose,' appears to be the first who attempted to give any notion at all approaching to reality of the animal, the result of a note and drawing which had been sent to him from India. Though the materials were too incomplete to furnish secure data for fixing its position, they gave information which former authors had not enjoyed, and there was certainly enough to prevent D'Argenville from placing it in the heterogeneous third division of his system, denominated by him the Multivalves. Linnæus arranged it immediately after Patella, and before Serpula, stating the animal to be a Terebella, and the shell to be univalve, tubular, straight (recta), monothalamous, and pervious at each extremity. Bruguière gave it nearly the same position: but if both these zoologists were right in making Dentalium follow Patella, they were as far wrong in placing it by the side of Serpula, Teredo, Sabella, and above all, Aspergillum. Lamarck, in his 'Système des Animaux sang Vertèbres' (1801), arranged Dentalium with Terebella,

and other genera analogous in appearance. In the Philosophie Zoologique' he separated the class of worms of the 'Système' into two other classes, and formed the Annelides, with the section of External Worms (Vers Extérieurs). He elevated, observes M. Deshayes, this division sufficiently in the series of Invertebrata, the presence of a heart and a circulation making it approximate to the Mollusks; whilst the Worms, very inferior in organisation, remained between the soft Radiata and the Insects. In this new class, adds M. Deshayes, we find the Dentalia in the same section with Serpula, Spirorbis, and Siliquaria. This arrangement was not altered in 'L'Extrait du Cours,' published in 1811. But, in the great work of the 'Animaux sans Vertèbres,' Lamarck, assisted by the labours of Savigny, and deceived moreover by the communications of M. Fleuriau de Bellevue, considered Dentalium as approximated to Clymene, and placed it in the family of Maldanians of M. Savigny. Systematic authors generally, not knowing more than Lamarck did, that knowledge being confined to the tube, followed Lamarck's opinion. Cuvier, in the first edition, placed it among the Annélides Tubicoles, between Aspergillum (Penicillus, Lam.) and Siliquaria. Savigny, in his 'Système des Annélides,' gave a summary description of the animal, but it was too incomplete to decide the question finally, though sufficient to overthrow the observations of M. Fleuriau de Bellevue. The D. Entalis, which was sent to Savigny by our countryman Leach, gave sufficient information to that celebrated zoologist to enable him to say that the animal had no trace of rings, that it had no hairs (soies) on the lateral parts of the body, that it was essentially muscular, and that it could no longer remain among the Chatopods.

D. Entalis was the species on which M. Deshayes made his observations; and in a very interesting and elaborate paper read before the Society of Natural History of Paris, on the 18th of March, 1825, he gave the facts which led him to the conclusion stated at the commencement of this article. The following is a summary of his description: but we must premise that M. Deshayes's specimens were forwarded to him in spirit, and were consequently a good deal contracted:

Externally the animal is conical and elongated, like the shelly investing tube (dorsal surface corresponding with the convexity of the shell; ventral surface corresponding with the concavity); smooth and truncated obliquely at the anterior end, the centre of the . cation with a small pyramidal process, which is the extremity of the foot. The posterior parts are less muscular, and the termination is usually a funnel-shaped expansion, variously developed in different individuals; for in some it is firm and well developed, and in others it is scarcely perceptible. This expansion is separated from the rest of the body by a strongly-defined contraction. There is a muscular ring, broader on the ventral than on the dorsal surface, above this contraction, and by that ring the animal is attached to the shell, which on its inner surface presents, at about one-fifth of its length from the posterior extremity, a corresponding impression in the shape of a horse-shoe, the interrupted portion being on the concave side. On the dorsal surface a small elevation is perceptible, at about one-third of its length from the anterior end, indicating the place of the head. The whole extent below this is occupied by two muscles on each side, distinctly observable through the abdominal parietes. These muscles are symmetrical, flattened, and directed obliquely from the sides of the foot towards the dorsal surface and the posterior extremity of the animal, giving rise to and becoming commingled with the muscle of attachment. On the abdominal surface, likewise, there are on each side, at about one-third of its length from the anterior end, two symmetrical organs deeply jagged, and of a dark brown colour: these form the liver. Below this point, nearly the whole of the abdomen is visible through its transparent parietes filled by granulations contained in the very large ovary, and by the straight descending intestine which terminates at the expanded extremity in a mesial vent. The whole of the anterior part of the animal is invested by a fine membrane, which is fixed posteriorly to the origin of the foot, and is free in front, where its circumference is thickened. It is perforated in its centre, and M. Deshayes considers this to be the mantle. The thickened portion is produced by a circular sphincter, which, when contracted, wrinkles the skin, closely embraces in its opening the extremity of the foot, and thus cuts off any external communication. M. D'Orbigny, jun., who furnished a drawing of the living animal in an expanded state, makes the dilated lobes of the foot resemble a flower whose undulated and small corolla supports in its centre a pistil thickened towards the middle, and pointed at its free end.

projects a little into the abdominal cavity, giving support to the stomach and the other principal viscera.

The head consists only of a mouth, and is situated superiorly at the hinder extremity of the foot. It is bell-shaped, and flattened from before backwards. Two black points on its sides might be mistaken for eyes, but these are the jaws situated within the mouth, and visible through the thin substance of which it is composed: they are spherical, horny, rough on their outer surface, cleft in the middle, and bearing a considerable resemblance to a small bivalve shell. There are two lips deeply cleft at the margin, or, more properly speaking, furnished each of them with three pairs of labial tentacles, those of the posterior lip, the middle pair especially, being much larger than

appear.

The foot is elongated, subcylindrical, slightly conical, and flattened from above downwards, fleshy throughout, and situated at the interior and anterior part of the head, having its upper and under surfaces slightly grooved in the middle. The anterior extremity is largest, and its centre is occupied by a sort of conical nipple, broader at its base, being there partly covered by two small notched lateral lobes, the notches corresponding with the grooves of the foot. The posterior extremity has a bifurcated appearance, owing to the attachment there of the retractor muscles; its middle portion

1. Shell of Dentalium Entalis, natural size. 2. Shell magnified, broken longitudinally, showing the animal in a contracted state; a, the posterior extremity prolonging itself into a small accidental tube. 3. Magnified, representing the animal at the moment of its advancing out of the shell; a, b, the foot, the lobes of which are developed in the form of a corolla; c, a part of the b, the collar; c, c, the mantle; d, d, the liver; e, the intestine; f, the ovary; collar. 4. The animal magnified, abdominal aspect; a, extremity of the foot; the muscle of insertion; j, h, the pavillon and its neck; i, the vent 5. Magnified, dorsal aspect; a, extremity of the foot; b, the collar; c, c, the mantle; d, slight projection produced by the head and the branchia;,, internal retractile muscles; f, f, external retractile muscle; 9, neck of the pavillon; h, the pavillon. 6. Magnified: the mantle has been slit in the dorsal and mesial line, detached in part from its posterior insertion, and turned aside showing, a, the extremity of the foot which closes the aperturej, of the collar 1, m, of the mantle n, o, p; b, b, lobes of the foot; c, the foot itself, presenting a depression or channel running its whole length; d, the head; e, the membranes; h, h, i, i, the branchiæ; P. P, 4, 9, the retractor muscles; cerebral ganglion; f, f, the two buccal jaws; 9, 9, the pedicles or branchiferous muscle of insertion; t, the neck of the pavillon. 7. fig. 4 natural size. 8. fig. 5 natural size. (Deshayes.)

the