indeed, generally white but sometimes black, bred about Lassa; wool very fine and like the shawl wool. 4th. Changumpo Look, abundant about Geroo and in Dingcham, generally very large; the white wool very fine and soft. The flesh of all these sheep is fine-grained and good. Of the Phák or pig there are two varieties, the southern pig, which is similar to the Indian village pig, and the small Chinese pig. There are no wild hogs in Thibet. The Chinese butchers at Lassa blow their pork so as to give it a deceptively fine appearance.

Ducks and geese are not eaten by the Thibetans, but are greatly used by the Chinese, for whom they are specially bred in Lassa.

The lakes of Thibet are full of fish, of which only one kind, named Choolap, is described; it grows to the weight of 8lb., and is a coarse food. It is, however, caught and preserved largely; the fish being gutted, split up, the tail put in the mouth, and dried, without salt, in the open air. Thus prepared they will keep for a year. The mode of catching them is singular; when the lakes are frozen over, a hole is made in the ice, to which they rush in such abundance that they are pulled out by the hand.

There are no leeches or mosquitoes in Thibet, nor are maggots or fleas ever seen there; and in Dingcham or Thibet Proper there are no bees or wasps.

Dr. Campbell gives us some very interesting information regarding the food of the Thibetans. During the summer months they use very little fresh meat. They do not like it boiled, and are not partial to it raw, unless it has been dried. In November there is a great slaughter, and a wealthy man, who has perhaps 7,000 sheep, will kill 200 at this time for his year's consumption. The animal after being killed is skinned and gutted and then placed on its feet in a free current of air. In a couple of days it becomes quite hard and is then ready for eating. It is kept in this way for more than a year without spoiling, even during the rainy periods. When long exposed to the wind of Thibet it becomes so dry that it may be rolled into powder between the hands. In this state it is mixed with water and drunk, and used in various other ways. The Thibetans eat animal food in endless forms, and a large portion of the people live on nothing else. The livers of sheep and other animals are similarly dried or frozen, and are much prized, but to strangers they are very distasteful for their bitterness and hardness. The fat is dried, packed in the stomachs, and then sent to market or kept for home use.

With regard to edible vegetables, it is stated that wheat, barley, and buckwheat sown in April or May and irrigated, are reaped in September, barley in Thibet taking the place of potatoes in Ireland, four-fifths of the population living on it. Besides these, the other crops are composed of peas, turnips, and a little mustard. The grain is ground in water mills. The bread is all unleavened, and cooked on heated stoves or gridirons. The sweet pure farinaceous taste of the fine flour equals the best American produce. The staple food of the country is champa, called suttoo in India; it is finely-ground flour of toasted barley. It is much eaten without further cooking; mixed up with hot tea it is called paak, and when prepared with tepid water it is known as seu. If any of our readers wish to enter upon "pastures new in the breakfast department, they may try Tookpa, which, to be properly appreciated, should be taken at daybreak before any matutinal ablutions. It is a sort of broth made with mutton, champa, dry curds, butter, salt, and turnips.

Goats are also reared in considerable flocks, but for their milk rather than their flesh. The milk of yaks, cows, sheep, and goats is used alike for making dried curds and the various preparations of milk used by these people. Mares' milk is not used in Eastern Thibet.

We now proceed to notice the mineral wealth of this remarkable country.

Pen, a carbonate of soda, is abundant south of the Yaroo; it appears in a whitish powder on the soil, never in masses underground. It is not used for soap-making or otherwise in the arts, but is always put into the water when tea is made, and is much employed medicinally.

Chulla, borax, is only obtained north of the Yaroo, whence it is imported to other parts of Thibet, to India, vid Nepaul, Sikkim, and Bootana, and thence to Calcutta and Europe.

Sicha, saltpetre, is abundantly manufactured in the Cara Thibetan sheep-folds, where composts of sheep's dung and earth are found to produce it.

Lencha, common salt, occurs in commerce in three forms, viz.: Sercha, white and best; Cháma, reddish and good; and Pencha, yellowish and bad, containing soda or magnesia and earthy matter. All the salt used in Eastern Thibet is the produce of the lakes and mines north of the Garoo, or comes from Lache, a district between Digarchi and Ladak. According to the best information, all the salt is the produce of lakes, while some assert that it is dug out of the earth. It is certain that the salt-producing districts are all but inaccessible, and can only be traversed by men and sheep; and that their elevation prevents the working from being carried on except in the warmer part of the year, from April to November. Thousands of sheep are employed in carrying the salt to places accessible to yaks, the former animals carrying a load of 20lb. to 24lb. on open places, or of 8lb. to 10lb. in the rugged vicinity of the deposits, whose elevation is not less than 22,000 feet, while the latter are capable of bearing a load of 160lb. Ser, gold, is found in the sands of a feeder of the Garoo, on its northern side, but the name of the river could not be ascertained by Dr. Campbell. The Garoo itself does not yield any gold washings. Most of the gold of Thibet is the produce of mines or diggings.*

Pabea, the yellow arsenic of commerce, is found west of Lassa, near the borders of China.

There are no mines of iron, silver, copper, quicksilver, lead, or coal in Thibet; the latter substance is, however, imported from China.

The turquoise, real or artificial, is universally worn in rings, necklaces, &c., and large, amber-like beads are a favourite ornament; but it is uncertain whether they are natural products of Thibet. The latter are apparently composed of turpentine mixed with some hardening material. Numerous imitations of turquoise are imported from China; and real but not valuable stones are sent, vid Cashmere (but from what locality is not stated). The only test of a real stone that is resorted to by the Thibetans is to make a fowl swallow it; if real it will pass through unchanged.

In conclusion, we may add that Dr. Campbell's articles in The Phenix contain much valuable matter on the geography, the government, and army of Thibet, the personal habits, customs, and ceremonies of the Thibetans, their religious festivals, the seasons, soil, and agriculture of the country, the wages of labour, and the most prevalent diseases. Amongst "Things not generally known," we may mention Goomtook, or The laughing disease, which consists of violent fits of laughter with excruciating pain in the throat. It equally attacks men and women, and often proves fatal in a few days.

ON THE CAUSE OF FIXED BAROMETRIC VARIATIONS

THE chief difficulty in the way of explaining the annual and diurnal variations of the barometer by the heating and cooling of the air, appears to be the existence of a double maximum and minimum. To show how such a double maximum and minimum might result from the

*Notices of the Thibetan Gold Mines may be found in several recent numbers of the "Proceedings of the Royal Geographical Society."

many species of Cicindela, or tiger beetle. The common English species, "C. campestris, frequents grassy banks, and is of a beautiful green colour, while C. maritima, which is found only on sandy sea shores, is of a pale bronzy yellow, so as to be almost invisible." He then states that a great number of species found by himself in the Malay Archipelago were similarly protected. "The beautiful Cicindela gloriosa, of a deep velvety green colour, was only taken upon wet mossy stones in the bed of a mountain stream, where it was with difficulty detected. A large brown species (C. heros) was found chiefly on dead leaves in forest paths; and one which was never seen except on the wet mud of salt marshes, was of a glossy olive so exactly the colour of the mud as only to be distinguished when the sun shone, by its shadow. Where the sand beach was coralline and nearly white, I found a very pale Cicindela; wherever it was volcanic and black, a dark species of the same genus was sure to be met with." But little attention has been given to adaptive colouring among the lower invertebrate animals. Darwin, in his last work on the "Descent of Man," calls attention to the statements of Haeckel that the transparency of the Medusæ and other floating animals is protective, since their glasslike appearance renders them invisible to their enemies, though Wallace also alludes to this same feature (p. 258). Mr. Edward Burgess informs me of a species of Acaleph, Polyclonia frondosa, on the coast of Florida which lives in the mud, and is brown in colour. Darwin, while admitting that the transparency of these animals unquestionably aids them to escape the notice of their enemies, yet doubts whether the colour of mollusks affords similar protection. He says, "The colours do not appear in most cases to be of any use as a protection; they are probably the direct result, as in the lower classes, of the nature of the tissues, the patterns and sculpture of the shell depending on its manner of growth" (vol. i. p. 316).

In glancing over our New England Mollusca, however, it seems that we do have very clear evidences of protective adaptations among them, not only in their form, but more particularly in their colour. It would seem strange indeed if this were not so, since so many species of Mollusca form an important portion of the food of many fishes,* and also of certain species of birds.

In a general way, we recall the sombre colours of the shells of most species, varying through different shades of yellow, brown, and green, in this respect resembling the sand, mud, and rocks, or seaweed, in or upon which they live, and we then recall by groups the land snails of our woods, with their almost uniform brown tints, like the dead leaves or rotten wood in which they live.

The freshwater snails have similar shades to match their peculiar habitats.

The freshwater mussels, coloured likewise brown, greenish, or black, accord with their places of refuge.

Among the marine forms we notice the adaptive coloura tion of certain species very well marked The common Littorina of the coast swarms on the bladder weed, the bulbous portions of which are olive brown in colour, or yellowish, according to age. The shells of the Littorina found upon it, present in their varieties these two colours, and are limited to these colours, though now and then delicately banded specimens are seen.

Purpura lapillus, which generally hides beneath overhanging ledges, or is concealed under flat rocks, has gene* In an inlet near Salem the writer observed a school of minnows swimming along the bottom, and as they approached a certain point jumped right and left in great alarm. For some time the disturbing cause could not be found. On closer examination, however, a Cottus was seen to open his large mouth and take in several of the little fishes. The Cottus was so perfectly protected

rally a dirty white shell, with, now and then, a specimen bright yellow, or banded with brown. We are not aware of any fish that feeds upon this species, though in the almost universal white colour of the species an adaptive colour may be secured in resembling the white barnacles which oftentimes whiten the rocks by their numbers.

In pools left at low tide where the rocks are often clothed with the red calcareous algæ we find the little red Chiton. Certain Mytili are green. The young of the large M. modiolus has a rough coat of epidermal filaments, | looking like the aborescent growth of some Alga or Hydroid.

The few species common to the mud flats exposed by the retreating tide are coloured black or dark olive. Ilyanassa obsoleta has the shell black, while the soft parts are quite dark. A related form, Nassa trivittata, lives in more sandy places, and has a similarly coloured shell. Rissoa minuta, inhabiting mud flats, has a shell dark olive, or nearly black, while other species of Rissoa are much lighter in colour. The fronds of the large Laminarian are frequented by Lacuna vincta and its variety fusca. The first is greenish or purplish horn colour, with darker bands, while the variety fusca is uniformly dark brown or chestnut; the colours in both cases quite match the Laminarian upon which they are found. Another species of the same genus, Lacuna neritoidea, Mr. Fuller has observed spawning on bladder-weed, and its yellowish tinge accords well with its surroundings. Margarita helicini I have found in numbers on the large Laminarian, and on seaweed at low-water mark, and its colour is decidedly protective; while other species of Margarita, dredged in deep water on shelly ground, are whitish, pearly, or red.

The protective colouring of certain species is well seen upon stones dredged in deep water, the various mollusks adhering to them closely resembling the calcareous algæ and the stones themselves.

Species similar to sand beaches are of various sandcoloured shades, as for example Machara, Mactra, Cochlodesma, Cyprina, the little Solenomya, and Solen. On muddy ground we notice certain Tellinas and other species with white shells. It has been supposed that those species hidden from the light were generally white, and this would seem to be the case when we recall Mya, certain species of Teredo, Tellina, Pholas, and other species. Yet we do have cases where the shell is oftentimes conspicuously banded or marked. It might appear that in those species living buried in the mud or sand, the shell was protected by a very thin epidermal layer, and that this layer was eroded, thus exposing the white shell; there are certain species, however, living buried in the mud or sand, which have an epidermal coat, very thick, and dark brown or black: such examples are seen in Solenomya borealis and Glycymeris siliqua.

It has been noticed that the same species occupying different stations are differently coloured. Dr. A. A. Gould noticed this in regard to Astarte castanea; those thrown up from deeper water are darker coloured than those found in quiet sandy places. In his "Report on the Invertebrate Animals of Massachusetts," first edition, p. 78, speaking of the shells found in the sandy harbour of Provincetown, he says: "The colour of all the shells in that harbour is remarkably light."

A very evident case of protective colouring is seen in the three species of Crepidula found on our coast. Crepidula fornicata is drab, variously rayed and mottled with brown, and it lives attached to stones near the roots of the large Laminarian, or upon stones clothed with algae of similar colours, or attached to the large Mytilus. Cre

and only then were the minnows alarmed. Just beyond in their track was a rusty tin fruit can, the little tin remaining on it reflecting the rays of the sun, and from this harmless object they all turned affrightedly away. In this connection it would be interesting to inquire into the food of fishes in respect to their colours. Those fishes feeding upon Mollusca would certainly not require that protection for concealment as those living upon more active prey.

roots of seaweed. Prof. Perkins records its occurrence on the black shell of Ilyanassa obsoleta. This Crepidula has a very dark brown shell, according well with the dark colour of its various places of lodgment. Crepidula plana

or unguiformis lives within the apertures of larger species of Gasteropods, as Buccinum, Natica, Busycon, and others. The shell of this Crepidula is absolutely white.

There are many species that undoubtedly receive protection in allowing foreign substances to grow upon their shells, and these species, oftentimes covered by a dense growth of calcareous or other algæ, are difficult of detection by the experienced collector.

There are also certain species that habitually accumulate foreign substances upon their shells. The little Pisidium Jerrugineum possibly finds greater immunity from danger in its habit of accumulating a ferrugineous deposit on that portion of the shell most conspicuous. Nucula delphinodonta has likewise a similar habit. The delicate Lyonsia arenosa, with its habit of entangling particles of sand in its epidermal filaments, undoubtedly finds protection in this peculiarity.

It was not the intention to go outside of New England species in citing these examples, but in this connection I cannot forbear mentioning the tropical genus Phorus. The species are said to frequent rough bottoms, and to scramble over the ground, like the Strombs, and not to glide evenly. This peculiar manner of moving would render them very conspicuous, and it is curious to observe that most of the species attach foreign substances to the margins of their shells as they grow, so that when a shell has attained its growth, it is almost completely concealed by fragments of shells large and small, spines of Echini, bits of coral, and stones.

These few observations are offered (and they might be multiplied) with the belief that if there is any truth in the theory of protective colouring, as advanced by Wallace, the various colours of Mollusca in many cases can be explained, and the occurrence of varieties in colour are also accounted for by the same theory.

EDWARD S. MORSE

attending the ordinary meetings of the Board, but also the various sub-committees on which the general working of the Act devolves, as well as the divisional and district committees, on the efficiency of which the local benefit of that Act depends.

"If you send me to the London School Board, I shall be prepared, while looking forward to the gradual adoption of a National system of Education, to adhere to that wise and moderate compromise by which, without violation of principle, you may obtain the use of existing school machinery.

"I have the honour to be, Ladies and Gentlemen, your obedient servant,

"J. J. SYLVESTER, LL.D., F.R.S. "Central Committee Room,

25, Great Quebec Street, Marylebone Road, W."

Dr. Sylvester has already received the promise of the support of the following scientific men :-Sir Chas. Wheatstone, D. C. L.; Prof. Sharpey (Sec. Royal Society); Prof. Busk, Pres. Royal Col. Surgeons; Phillip H. Calderon, R. A.; William Heywood, C. E.; E. H. Lawrence, F.S.A.; J. Norman Lockyer, F.RS. J. Gerstenberg, F.R.G.S.; J. Gwyn Jeffreys, F.R.S.; Nicholas Trübner, M. R. A.S.; Prof. T. Hewitt Key, F.R.S.; Dr. Wilson; David Forbes, F.R.S.; H. W. Bates, Sec. Royal Geog. Society; Henry Holiday; Henry Watts, F.R.S.; Dr. Pick; Thomas Woolner, A.R. A.; Professor Williamson, F.R.S.; Charles Brooke, F.R.S.; Sir Henry Thompson; Colonel Stuart Wortley; Dr. Forbes Winslow, F. R. S.; Joseph Durham, A.R.A.; C. Murchison, M.D., F.R.S.; Prof. Henry Charlton Bastian, F.R.S.; William Perkins; Noel Humphreys, F.S. A.; T. Spencer Cobbold, M.D., F.R.S.; A. W. Bennett, F.L.S.; Sir Julius Benedict; Prof. W. Warrington Smyth, F.R.S.; George Cruickshank; Prof. J. Percy, F.R.S.; George Harley, M.D., F. R.S.; Nevil S. Maskelyne, F. R.S.; W. S. Dallas, Sec. Geol. Soc.; Prof. G. C. Foster, F.R.S.; William Chaffers, F.S. A.; J. J. Stevenson, F.R.G.S.; and J. H. Pepper.

SCIENCE AT THE LONDON SCHOOL BOARD

PROF. J. J. SYLVESTER has issued his address

as candidate for election to the London School Board for Marylebone in the room of Prof. Huxley. The importance of having at least one representative of Science on the Board induces us to print his Address in full. It must be obvious that many subjects will come before the Board wherein the opinion of a man of Prof. Sylvester's scientific training will be of the highest value; and we heartily wish the Board may be fortunate enough to obtain the additional strength which will be secured by his election.

"LADIES AND GENTLEMEN,-An influential body of ratepayers have appealed to me as a man of science, to offer my services on the London School Board.

"It has been represented to me, as the wish of your great constituency, that Prof. Huxley should be replaced by one who, like himself, has made the scientific part of education the chief business of his life. On this ground I have ventured to place myself in your hands.

"My University career at Cambridge, added to my experience both as Professor of Natural Philosophy at University College, London, and subsequently as Government Professor of Mathematics during a period of fifteen years at the Royal Military Academy at Woolwich (from which I have recently retired), have given me considerable knowledge of educational matters in England. My position as Corresponding Member of the Institute of France, as Corresponding Member of the Royal Academy of Science of Berlin, as Foreign Member of the Royal Academy of Science of Naples, and other learned corporations, gives me an early and accurate knowledge of what is passing in the chief intellectual centres of the Continent. I have ample leisure for the work that is to be done, not only in

NOTES

WE Congratulate the Science and Art Department on a resolution at which they have just arrived, in consequence of applications from science schools, to form collections of such specimens, models, diagrams, &c., as are best adapted for teaching the various branches of science which the Department aids by grants. It is proposed that collections shall be sent on loan for short periods to the local schools, to assist them in furnishing themselves with the necessary apparatus. The specimens and appratus already in the Educational Department of the South Kensington Museum have been arranged for examination under the different subjects of instruction, and a letter has been forwarded to all the Examiners of the Department, requesting them to inspect the collections, with the view of advising what portion of them they consider may with advantage form part of the proposed travelling collections; what additions should be made, so as to give the science schools an idea of what they would require for a complete outfit; and what are the best and cheapest forms of apparatus, &c., for them to provide themselves with.

A FEW months ago we noticed the expedition to Moab which, by the aid of the British Association, was organised by Dr. Ginsburg and Dr. Tristram. We have now to announce the safe return of Dr. Ginsburg, and hope soon to be able to state some of the results of the expedition, which we have reason to believe are both numerous and interesting.

THE Society for the Encouragement of Arts, Manufactures, and Commerce is about to organise examinations in the science and technology of the various arts and manufactures of this country, which shall be conducted by a Board of Examiners, capable of testing the practical knowledge and skill required in the application of the scientific principles involved in each art 91