The thermometer, too, is indicating a diminution in the temperature as we rise; so, indeed, are our feelings, making us wrap ourselves in our great-coats. Mr. Welsh tells us that "the temperature of the air decreases uniformly with the height above the earth's surface until at a certain elevation, varying on different days, the decrease is arrested, and for the space of from two thousand to three thousand feet the temperature remains nearly constant, or even increases by a small amount; the regular diminution being afterwards resumed and generally maintained at a rate slightly less rapid than in the lower part of the atmosphere, and commencing from a higher temperature than would have existed but for the interruption noticed." Rising above the region of clouds, we get into a space where the temperature is below the freezing point; and this explains to us why, even in the height of summer, lofty mountains are always covered with snow.

If we have provided ourselves with winged animals, as Gay-Lussac did, we may now let them fly. He tells us, that at the height of 8600 feet a bee was liberated, and flew away humming briskly. A linnet set free at 11,000 feet, before adventuring into the rarefied medium, settled for awhile on the stays of the balloon, and then dashed downwards perpendicularly. A dove, after hesitating awhile, whirled in great circles, and swooped earthward through a mass of cloud.

Floating majestically through the cold, clear air of these upper regions, with the sun shining in unbroken splendour across the deep blue heavens which have never known a cloud, we consider our various observations with the hygrometer, and also upon the mists through which we have passed; but these require much arrangement, and before we give the results of them we must descend to terra firma, and gain some breathing time. J. H. G.

THE LYMINGTON BRINE SHRIMP,* AND THE FEZZAN WORM.†

In the reservoirs belonging to the salt-works of Lyming ton, in Hampshire, there occurs in great abundance a very pretty little animal belonging to the entomostracous crustacea, somewhat resembling a minute shrimp. In 1755 Dr. Schlosser, a German naturalist, visited these salt-works, and upon examining the salterns was surprised to observe the whole cistern tinged of a red colour. The liquor which was contained in the cistern, was the brine previous to its being boiled, and contained nearly a quarter of a pound of salt to a pint of water. He soon detected the cause of the colour. It depended upon the presence of an immense number of small animals of a reddish hue. In this

strong, concen

trated solution of

b

salt, which is sufficient to kill almost every other living animal, these little creatures were sporting about in all the enjoyment of existence. They are very slender, linear in form, and do not exceed from a quarter to half an inch in length. Their head is furnished with two hornshaped appendages, and on each side of the body is a row of foliaceous-looking feet, eleven in number. "There is nothing," says Joly, another observer, "more elegant than * Artemia salina, fig. 1.

† Artemia Oudneyi, fig. 2. The figures marked a are the natural size. The other figures are magnified representations of the several parts.

the form of this little crustacean; nothing more graceful than its movements. It swims almost always on its back, and by means of the fins of its tail, it moves rapidly in all directions through the element it inhabits. Their feet are in constant motion, and their undulations have a softness difficult to describe." The workmen at the saltworks believe that these little creatures are very useful, from their incessant motion, in causing the liquor contained in the cisterns to clear; and they often transport some of them from one saltern to another, in order to have a supply for that purpose. These elegant little animals when taken out of the water and placed in spirits of wine, are nearly white; and it has been lately proved that their red colour depends upon the presence in the water of myriads of an exceedingly minute infusorial animalcule, a species of the genus Monas, which is of a red colour, and forms the principal food of the brine shrimp. This interesting crustacean belongs to the genus Artemia; and the species above mentioned is the A. salina. Several other species have been described, all residing in salt marshes or ponds abounding in salt. The late Dr. Oudney, in his travels, along with Major

α

Denham and Captain Clapperton, into Northern and Central Africa, gives an interesting description of a species he observed in Fezzan. Monday, July 8, 1822," he says,

66

66

we entered the Wady Trona early this morning. Near where we entered there are a cluster of

date-palms, and a small

lake from which impure trona (saltpetre) is obtained. It is

AND THE FEZZAN WORM.

231

about half a mile long, and 200 yards wide." The scene which here met his view seems to have made a great impression upon the traveller. Clapperton, he tells us, was sitting on the top of a high sand-hill, and so pleased with the view that he called out several times to him to dismount from his camel to enjoy the treat. The appearance was beautiful. A deep sandy valley lay spread out below them, and though its sides were dry, bare, and without vegetation, it contained in its bosom two large groves of date-palms, within each of which a fine lake was enclosed- an oasis in the Desert. All around was dreary, hot, and dry, but here the beautiful date-palm tree rose majestic, and the cool water of the lake rippled in the breeze. It was in these lakes, highly charged with saltpetre and muriate of soda, or common salt, that the little Artemiæ resided.

They occurred in immense numbers, were well known to the natives as the Fezzan worm, and highly prized by them as an article of food. They are most abundant in the spring, though they are to be found at all times, and appear on the surface in particularly large quantities during high winds. The natives fish for them with a long hand-net. A man wades some way into the lake, and after allowing the net to remain some time at the bottom, it is taken up, or drawn a little along the ground, and in this manner several pints are sometimes caught at one time. They are placed in the sun's rays for a few hours to dry, and in that state sell at a high rate in the different towns in Fezzan. These little crustacea have been observed by a more recent traveller in the same country, Dr. Vogel, who was despatched in the beginning of last year to join Dr. Barth, now conducting the African expedition, by orders of H.M. Foreign Office. He has sent home a drawing, made by himself on the spot, of the Fezzan worm, which he calls the Dūd, and which corresponds well with the description given by Dr. Oudney.

Dr. Vogel says, "The colour of the worm is reddish, and exactly the same as that of the goldfish. In swimming, its movements resemble those of a serpent, and its feet are constantly paddling very quickly. It has eleven or twelve feet on each side. During the daytime the worm retires deep into the lake, and only appears on its surface in the morning and evening. They are caught in cotton-nets, in which are hauled up at the same time innumerable flies and other insects with which the lake is filled. The whole is mixed with a red kind of date and made into a paste, which has a similar smell and taste to that of salt herring, and which is used by the inhabitants of Fezzan in the place of meat, along with bazeen and other puddings."

This species, which has never been named, we propose calling Artemia Oudneyi, in honour of its first describer, Dr. Oudney- a slight tribute to the memory of a traveller who laid down his life in the cause of African discovery, and one which we feel sure Dr. Vogel will recognise with pleasure. The length of a full-grown Dūd, according to Dr. Vogel, is 37ths of a Paris line, and the breadth close under the head, 1ths of a line.

For the annexed figure and above-quoted remarks, we are indebted to the kindness of Mr. Augustus Peterman, Physical Geographer to the Queen. They were contained in a letter to him from Dr. Vogel, and politely placed at our disposal.

Dr. Vogel is by profession an astronomer, and was for two years assistant to Mr. Hind; but his enthusiasm for the cause of science impelled him to undertake his present perilous expedition. In addition to astronomy, Dr. Vogel is an excellent botanist, and no doubt other branches of natural history will receive his attention. Interesting news may, therefore, be daily expected from Lake Tchad.

W. B.