I have found that the colour decreases in lustre by the animal being kept for any time out of its natural element. From the experiments upon the Turbo Clathrus I quote the following :—

"As the animal becomes sickly by keeping for some days in sea-water, it frequently discharges a most beautiful purple liquor. This circumstance was known to Plancus, who observes that it was one of those shells which yield the purple dye of the Mediterranean; and which is also recorded by Martini. It may, indeed, with much reason, be conjectured that this is really one of the shells from the animal of which the ancients procured their famous purple dye; though if Pliny is consulted, the shells that produced this precious colour were either Murices or Buccines, or both. 'Glowing with Tyrian Murex,' is an expression of Virgil, that indicates it to have been collected from shells of that genus only; but we must recollect that conchology was, at the time of those writers, in its very infancy; scarcely systematized, or formed into any divisions, so that Turbo Clathrus may possibly have some claim to the credit of contributing to the celebrated Tyrian Murex."

The colour of this animal differs, however, materially from that of the Buccinum Lapillus, for

"Mineral acids turn it to a bluish green, or sea-green; sulphuric acid renders it a shade more inclining to blue: vegetable acids probably do not affect it, since cream of tartar did not in the least alter it. These colours laid on paper, were very bright, and appeared for some months unchanged by the action of the air, or the sun; but being exposed for a whole summer to the solar rays, in a south window, they almost vanished. The application of alkali to the acidulated colour always restored it to its primitive state, and was as readily changed again by mineral acid; in particular, it differs materially from the succus of Buccinum Lapillus, which we have before remarked is unalterable. Its property is materially different from litmus, which is turned from blue to red, with the most trifling mixture of any acid. It differs, also, from vegetable colours in general by not being affected by alkali, which turns the infusion of blue or purple flowers to green."

No reliance can, I conceive, be placed on the accounts of the ancients, as to what the exact animal was; some supposing it to have been a Purpura, some a Murex, and others a Buccinum or a Turbo; all of which do, no doubt, yield a dye, but the finding of the breccia of the Murex Trunculus, in the dye-pots at Tyre, is, I think, conclusive.

There is, I understand, a tradition among Irish antiquaries, that the shells were found on this coast, and that it was for this purpose the Tyrians voyaged so far west. This, however, is not very likely, when the shells that give the colouring matter were found, so abundantly, near home, and the Murex Trunculus is not found here; besides, unless they manufactured it on the Irish coast, it would be of little worth, for, unlike cochineal, the colour fades on the death of the animal.

Stone mortars, similar to those found at Tyre, were in use among the

ancient Egyptians; and several of the mummy clothes have a blue crossstripe above the end or selvedge. This colour, Mr. Thompson supposed to be the product of indigo, and this opinion is adopted by Mr. Wilkinson; but the tests used by the former, prove it as well to have been the Tyrian, or conchilian colour; and this is the more probable, from the Hebrews carrying along with them not only the art, but very likely the materials to manufacture it with, as I have endeavoured to prove in the previous part of this essay; and if it be established that all these colours were the produce, or, at least, the manufacture of Tyre, it proves the existence and commercial importance of that place as far back as when the Israelites wandered in the wilderness.

I trust some of our enterprising manufacturers will institute an inquiry as to the possibility of turning the shells producing a colouring matter, that inhabit our shores, to account. Some valuable information on this subject may be found in the work of Amati, called, "Purpura Restituta," Reaumur's Experiments on the Buccinum of Poitou, Duhamal's Experiments on the Mediterranean Mollusca, Fabius Columna De Purpura, Vitruvius De Architect, 1, 7, c. 13. See, also, Cuvier's Animal Kingdom, Donovan's, and most other conchological works.

N. PAGE 517.

ANATOMICAL CHARACTERISTICS OF THE HEADS FOUND IN THE ACELDAMA, AND DESCRIPTION OF THE CRANIUM OF A MODERN EGYPTIAN.

In the skull belonging to the Ethiopian variety, figured at page 515, the nasal bones are rather more prominent than in the generality of this race, and the tube of the ear is a little lower down than in most skulls that I have examined. Independent of the general characters of the heads of this variety, as I have enumerated them at pages 513 and 514, I may notice the following peculiarities or distinctions between that figured in the text and the European or Caucasian form of cranium.

Besides the greater density and strength of the malar or cheek-bone, it presents a much larger lateral surface than in the Caucasian, and a greater hollow or depression at its junction with the orbital process of the frontal. The posterior surface of the superior maxillary bone is, likewise, more convex externally, and the external pterygoid plates stronger. The other peculiarities of the lateral view are well exhibited in the engraving.

Professor Owen has, with his usual talent and observation, drawn attention to the analysis of the basis cranii of different skulls. A few words on the comparisons of this and the other crania represented in the text may not be amiss. The outline of the base is longer, and its sides flatter; the foramen magnum is more elliptical; but its anterior edge is on a plane anterior to the anterior margin of the mastoid processes. The occipital condyles look more outwards, the basilar process is longer and narrower

than in Europeans, the glenoid cavity is much deeper, and the hard palate is shallower and less arched.

The pyramidal skull of the Mongolian variety represented at page 516, differs, however, from the true or well-marked Mongolian in the following particulars:-The face is not quite so flat or confluent; the zigoma is not quite so prominent laterally, and more rounded at its junction with the malar or cheek-bone. The alveolar process, or the sockets for the teeth, projects rather much, so as to throw out the teeth at a small angle with the upper jaw, in this respect approaching the negro race; the nasal bones are more prominent, and have a very deep notch at their junction with the forehead or frontal bone. This peculiarity Dr. Prichard says he has observed in Australian and Polynesian skulls; but another head that I removed from the left-hand chamber of this tomb, wants this, and possesses more of the Chinese feature. And he also says, that he has seen Esquimaux heads, that they very much resembled, and that in some particulars they are like those artificially-shaped craniæ brought from Peru; but a glance at this skull, and at one of those altered by artificial means, will at once explain the difference. The orbits preserve much of this Mongul peculiarity, being long, large, deep, set widely apart, and having the lower edge on a plain posterior to the upper.

I know not whether the remark be original, but it has struck me as being extraordinary, that the knob at the top of this skull, which is so characteristic of the pyramidal heads to which this belongs, and which might be adduced as one of the characteristic distinctions of a particular race, is chiefly found among those nations who shave the scalp, except a long tuft of hair left at top, growing from this part of the crown of the head. Such is the practice, and such the heads among the Chinese, Kalmucs, and Turks, who are descendants of the Turcomans, a true Mongul race. Homer mentions that the Thracians, another Turanian people, wore the hair only on the crown of the head. I have frequently observed in the barber's shops in the east, that the heads of young boys did not possess this knob, even comparatively with the men; and from this circumstance I am inclined to suppose, that their wearing this tuft on the top of their heads, is partly the cause of the protuberance, especially as, when uncovered, they are constantly pulling and twisting it in their fingers.

The engraving of the mixed variety at page 518, is the skull of an old edentulous person, probably a female; so thin as to be almost diaphanous in many places, and is particularly light and friable. The zigomæ are slightly arched, and project somewhat beyond the lateral surface of the head. The nasal bones are rather prominent; the alveolar process is wholly absorbed, and the hard palate very narrow; the condyles are on a plane with the extremity of the mastoid processes. The want of frontal development, and extremely small size of this head, give it some of the characters of that of an idiot; but there were many such in the same chamber.

To enter into a more minute detail of all the anatomical characters of these heads would be foreign to a work such as this.

In the skull of a modern Egyptian who was killed before the walls of Acre, in the attack on that place by Ibrahim Básha, in 1836, and now in my collection, we have a well-marked instance of the generality of that people, who are characterized by extreme narrowness of breadth, as compared with the height of their foreheads; this skull barely measuring three inches above the external angular processes of the frontal bone. This is evidently a mixed variety, and exhibits in a very remarkable manner the blending of the anatomical characters of the two races from which the greater part of the modern Egyptians are sprung; that is, the Arab and the Negro. But many of the negresses who are sold in the Egyptian slave-markets are natives of Mozambique; and these, it is wellknown, have higher foreheads than any of the other negro races. The zigomæ are on a plane somewhat external to the frontal and parietal bones, and more arched than in the well-marked Ethiopian. The nasal bones are more prominent, while the alveolar process of the superior maxilla presents all the characters of that race. The upper and lower margins of the orbits are on the same plane; the base of the skull presents a greater preponderance in its antero-posterior, compared with its lateral diameter; but the most striking peculiarity of this base is that of the projection of the occipital condyles below the plane of the mastoid processes. The sutures of this head are the most strongly marked that I have ever seen, and contain (particularly the lambdoid) the largest and greatest number of ossa triquetra I have ever met with.

0.-PAGE 565.

REGISTER OF THE FAHRENHEIT THERMOMETER, ON BOARD THE CRUSADER YACHT, TAKEN AT THE HOURS OF 9, A.M.; 12, N.; AND 9, P.M., FROM THE 9TH DECEMBER TO THE 23RD OF MAY, 1837-8.