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other descriptions of apparel usually worn by Continentalists during the winter months.

There yet remain two foxes that demand a passing notice, as being of some considerable importance to the furrier: the arctic fox (Canis lagopus), known commercially as the white fox, and the “ blue" arctic fox.

It is very difficult to discover the actual number of white fox skins annually imported into this country from the arctic regions, but if we assume nine thousand as being somewhere about the average number, we shall not be very wide of the mark. I find, on referring to the catalogue of the collection of animal products in the South Kensington Museum, that the number of undressed fox skins imported in the year 1856 was as follows:

From Hanse Towns . . . . . . . 1,588

United States . . . . . . . 4+,126

British North America. . . . 35,598 * Other parts . . . . . . . 175

81,487 From out of this heavy supply, 79,063 fox skins are re-exported to various cold countries. The chief demand for furs of this description is among the nations of Tartar and Slavonian es. traction. I may instance the Russians, Poles, Chinese, Turks, and Persians. Then, again, we have another market amongst the people of Gothic origin, who occupy portions of the middle and western parts of Europe.

White fox skins are deservedly celebrated for their beauty, and the extreme fineness of their fur; neither have they the pungent, disagreeable odour that characterizes the skins of the other species of foxes. The price for white fox ranged, at the March sales of last year (1866), from 4s. the lowest price, up to 19s. 6d, the highest, which gives an average of lls. 6d. per skin. As there were 7591 skins sold, the sum returned for white fox-skins would equal £4364 16s. 6d.

The arctic fox is principally found in the countries bordering the Frozen Ocean in both continents. It hardly needs any detailed description, because there are a great many specimens of this curious little animal in the Zoological Gardens in the Regent's Park, where five minutes' observation will do more to familiarize any person with its peculiarities than whole pages of description. As the cold and snows of winter approach, the coat of the arctic fox becomes exceedingly thick and ragged, and changes from blackish-brown, which is the summer colouration, to pure white. The winter jacket is therefore a most admirable protection; in the first place its thickness defies the extreme cold which prevails in high northern

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latitudes, and, secondly, its whiteness helps to conceal the animal when traversing the snow.

In nearly every book on arctic travel the white fox is referred to, and its habits described. Pennant tells us “ that in Spitzbergen and Greenland, where the ground is entirely frozen, they live in the clefts of rocks, two or three inhabiting the same hole. They swim well, and often cross from island to island in search of prey.” The Greenlanders trap them either in pitfalls dug in the snow and baited with fish, or in an ingenious kind of spring trap constructed of “whalebone.”

Sir John Richardson informs us that the arctic fox appears to be wanting in that extreme cunning for which reynard in general is so celebrated; "they will stand by whilst the trap is being prepared for them, and walk straight into it as soon as the hunter has left it."

It is an open question whether or not the “ blue fox” is a species distinct from the white, or only a different condition of age; and as I am not prepared with any facts likely to settle the matter one way or the other, I shall not attempt to enter upon any discussion concerning it. There were only about ninetytwo skins offered at the March sales, for the year 1866.

THE STRUCTURE OF THE ANNELIDS, WITH A

CRITICISM ON QUATREFAGES.

By EDOUARD CLAPAREDE.

(Continued from page 273.) Respiratory Apparatus.-"M. Quatrefages has actually made science retrograde in respect to the structure of the organs of respiration of Annelids. This is the weakest part of his book, alike in the introduction and in the generalizations concerning each family. The branchiæ have, according to the opinion of the honourable academician, a special structure, which permits them always to be distinguished. “ These organs," he says, “ are characterized by a single canal, to and from which the afferent and efferent vessels run. This canal, of which the walls are sometimes visible, and at others indistinct, is surrounded by a diahhanous substance, which appears to result from a thickening of the dermis. In this substance ampulla-shaped lacunæ are hollowed out, more or less developed, and always destitute of proper walls. The whole is surrounded by an epidermis extremely fine, and

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not presenting any appreciable structure. ..... At the close of a variable time the branchiæ contract, although no muscular fibres can be distinguished. The ampullæ empty themselves, and sometimes completely disappear. The blood runs by the central canal of the branchiæ, and arriving at the base of that organ, passes into the efferent vessel. In this return movement it necessarily meets with the venous blood, and must mix with a certain quantity of blood which has not been subjected to the action of air.” Bearing in mind this radically false description, let us see how the normal circulation takes place in the branchiæ of an Annelid. There cannot ordinarily be any mixture of arterial and venous blood. In fact, the artery goes to the extremity of the branchia, where it turns upon itself to return as a vein. Vein and artery are exactly parallel to each other. Throughout the whole length of the branchia these two vessels are placed in communication by a double series of vascular loops, which pass into the subcnticular layer, and which offers the greatest facility for the action of water charged with oxygen, through the very thin cuticle. As for the contractility of the pretended ampullæ, there is nothing of the sort. Certain genera, like the Terebellians and Telethusians, for example, exhibit many rythmical contractions all through the branchia, but not of the vessels themselves. Moreover, this fact is exceptional. In the family of the Serpulæ only do the branchiæ exhibit even a remote resemblance to the descrip. tion of M. de Quatrefages. In fact, in these Annelids the artery is continued directly into the vein at the base of the branchiæ, and from this point of reunion a single vessel proceeds, which penetrates the branchia, and sends a cæcum into each branchial branch. But M. Quatrefages describes in the secondary branches of the branchiæ of the Serpulians an apparatus of ampullæ, of which no trace exists. The blindvessel exhibits no ramification, it is simply cylindrical and contractile, as described by Grübe and Kölliker. In their branchiæ, the blood exhibits an alternating movement, which is exceptional. In all the other families the branchial circulation is continuous in one direction. Blind vessels with alternating circulation, are found in the tentacles of Spiodians, Amphictenians, and Pherusians; in one part of the so-called branchial threads of Cirratulians, but these organs are not respiratory (unless, perhaps, lymphatic). [M. Claparède then remarks on the way in which M. Quatrefages was misled, and observes that the point was cleared up thirty years ago by Grube.]

Reproductive Apparatus.—The reproductive apparatus of Annelids remains very imperfectly known. It is trae numerous works have thrown fresh light upon the educatory

organs known, since Dr. Williams described them, under the name of segmentary organs; but our knowledge of the sexual glands has made little progress for the last thirty or forty years. This memoir will, I hope, make these organs, in a great number of species, sufficiently known.”

M. Claparède then remarks on the very inexact description of M. Quatrefages, and continues :

“The distribution and conformation of the sexual glands of Annelids is subject to numerous variations, which will be illustrated by numerous examples in this memoir. The following may, however, be regarded as the most widely diffused. The sexual glands form more or less complex clusters or interlacements of cords, of which the axes are occupied by sanguiferous branches, often contractile. The sexual elements, when growing, form ruffs round the vascular axes, and develop at the expense of a layer of nuclei close to the vessel. With certain vesselless Annelids this form of sexual gland is preserved, but the axis is occupied by a solid cord, instead of a vessel. Among the females, the ovules are often in close juxtaposition in the ovary; sometimes, however (Owenia, Della Chiaje, and certain Polynoe), each one is inclosed in a special ovisac. In either case the eggs, on arriving at maturity, detach themselves from the ovary, either directly or indirectly, through rupture of the ovisac. The zoosperms detach themselves from the testicle to float freely in the perivisceral cavity. Doubtless this fundamental form is sometimes subjected to important modifications, to constitute, for example, the peculiar sexual tissue of the Nereidians, or the floating testicles of the Dasybranchians, which will be specially described. The eggformation of the Terebellians and Serpulians is still more divergent, but we always find a cellular tissue, fixed, or composed of floating materials, in the midst of which the sexual elements are developed. ....

“The sexual glands have long been recognized in many Annelids, but these old observations have been partly forgotten. Thus, while Pallas erroneously supposed the eggs of the Aproditians to originate in the liquid of the perivisceral cavity, Gott, R. Treviranus and Della Chiaje recognized the true ovaries at the base of the feet of these worms. ... Even the existence of a sanguiferous vessel in the axis of the sexual glands was not unknown.”

M. Claparède points out the errors of various authors, and adds:

“It is indubitable that Annelids exist which are destitute of segmentary organs, or in which they are reduced to simple openings in the back of the body.

Nervous System.-It is, without doubt, to M. Quatrefages

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and M. Leydig that we owe the best researches into the nervous system of Annelids. The first chiefly directing his attention to the external form of this system, and the second to its histology. ... M. Quatrefages has been so fortunate as to find a stomato-gastric system of nerves, similar to that of the Hirudinea. I have not been able to recognize it, but I am sure that a negative result is not of great importance in these difficult investigations. I am, however, astonished that the combined efforts of other observers have been equally unsuccessful. ... The structure of the nervous system varies astonishingly in the series of Annelids; the distribution of nerve-cells particularly being subject to a host of variations, which will be explained hereafter. In the ventral chain the cells belong chiefly to the surface and the sides, as Leydig has already noticed. The existence of large tubular fibres on the dorsal surface of the nervous chain, so general among the Oligochata, is confined among the Polychæta to a small number of families (Capitellians, Aricians, Spiodians, Syllidians, Eunicians), and even appear in some representatives only of these families.

The nerve terminations amongst the Annelids have only been studied hitherto by myself, and by MM. Keferstein and Kölliker. All these terminations appear related to the functions of touch. The nervous expansions of the organs of sight and hearing are little known, even in Alciope, notwithstanding the researches of Leydig. In reference to this subject, I may recal an opinion of Joh. Müller, which has fallen into oblivion. We owe to this great physiologist an excellent figure of the central nervous system, and of the eyes of the Nereids—à figure to which his successors have not added anything important. He does not consider the organ called a crystalline lens as a dioptric medium. He denies its transparency, and regards it only as a terminal enlargement of the optic nerve. Although the transparency of the crystalline body is in many cases incontestible, the opinion of Müller on the functional value of this organ should not be rejected. The eyes of Nereids and of most other Annelids appear destitute of all apparatus for accommodation. Admitting that the percipient elements are lodged between the granules of pigment, it could be only objects at a determinate distance that could project their images upon this choroid pigment, and the sight of the creature must be very limited. This difficulty disappears if we seek in the crystalline body at once a refractory medium and a percipient organ, as we are almost obliged to do in the crystalline cones of the Archropoda. ....

Restoration of Mutilated Parts.—The observations of Bonnet on the restoration of mutilated parts among the earth

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