crowns much worn down and hollowed out in the middle, showing the central brown dentine, surrounded with a coat of enamel, and a slight outer layer of dark coloured cementum.

m

9-9 = 36. 9-9

There are fifteen molar teeth remaining in the upper jaw, and fifteen in the lower, with six distinct empty sockets; the dental formula in the skull from Honduras is, therefore, It appears to have been from the American species, the Manátus australis of the British Museum Catalogue, that Daubenton, Cuvier, Gray, and others, have adopted the dental formula of the genus Manátus. In the British Museum Catalogue for 1850, the number of grinders in the genus Manátus is said to vary according to the age or 9-9 state of the specimens, but when complete to be m = 36.

9-9

It is added that the front ones are often deciduous; hence 6-6 6-6

Sir Everard Home describes them as m

Cuvier as m

8-8
8-8

= 32.

= 24, and

There is no skull of the African species mentioned in the Catalogue as existing in the British Museum; and there is none described in the Catalogue of the Royal College of Surgeons of London; and at a meeting of the British Association held at Cheltenham in 1856, Professor Owen stated, that he had not then had an opportunity of examining the dentition of the known African Manatee.

The difference in the number of the molar teeth in these two distinct species corresponds with the difference in the length of the aveolar portion of the palate, and with other corresponding modifications which have been shown to exist between the two skulls.

I am indebted to Professor H. D. Rogers of Glasgow for an opportunity of comparing the skull of the Manátus australis, with that of the Manátus senegalensis; and the result of this anatomical comparison appears to me to justify the 11-11

conclusion, that m

11-11

44, is the normal number of

the dental formula for the genus Manátus, as this number

was found to be present in the skull of the Manátus senegalensis, which inhabits the rivers at Old Calabar.

III. Historical Review of the State of our Knowledge respecting Metamorphism in the Mineral Kingdom, with special regard to certain recent Researches. By JOHN S. LIVINGSTON, Esq.

Mr Livingston stated, that within late years great additions had been made by the labours of chemical geologists to our knowledge of the more recondite geological phenomena. To these additions he wished to direct the attention of the Society, as they seemed in this country to have, in a great measure, escaped notice. After expressing his opinion that, if we are to make any advances in our knowledge of the deep-seated causes of metamorphic changes, it must be brought about by introducing into the methods of geological research much more of the experimental than had hitherto been considered necessary, he rapidly sketched the progress of inquiry into metamorphism. Every year was enabling us more and more to imitate the mineral productions that occur in nature, though we cannot reproduce all the conditions under which they were formed. What the influence of the long lapse of ages might have been, must of course ever remain an insoluble problem. After passing under review the opinions of Hutton, Mr Livingston referred to the experiments of Sir James Hall, but especially to his having succeeded in producing a crystalline marble, by placing powdered calc spar in a gun-barrel hermetically sealed, and exposing it to a high temperature,-an experiment that had been recently impugned by Gunstav Rose, but on insufficient grounds. Reference was then made to the processes adopted by Berthier, H. Daville, and Caron, for artificially producing minerals by fusion alone, and especially to the production of corundum by Ebelman. But the most important results were obtained when Senarmont, by experimenting on minerals with water at high temperatures, and under enormous pressures, produced crystalline quartz, spathic iron, sulphate of baryta, and sulphide of antimony. Daubrée in 1857 had, by using a temperature of 572° Fahr., converted wood into anthracite; and Baroulier in 1858 obtained coal

VOL. II.

2 M

by placing vegetable matter in moist clay, and exposing to heat. Daubrée's observations made at the thermal springs of Plombières were next mentioned. These issue, with a temperature of about 172° Fahr., from a porphyritic granite in the mountains of the Voges. To convey the water of the springs to the baths, which the Romans had built there, a structure of brick and sand had been erected. Through this the water had trickled. On breaking into the mass numerous minerals of the zoolite family were found, but chiefly Apophyllite and Chabasite. Mr Livingston then mentioned the extensive changes effected by the juxtaposition of certain rocks, and especially the phenomenon termed Endomorphism by Fournet. He then discussed the bearing of these and other facts, and showed that, though the hypothesis of a central fire would undoubtedly explain much, yet that it would not all. If heat were the only agent in these changes, he asked why did they not take place according to the known laws of the propagation of heat and the conductibility of rocks? That water had to do in effecting these changes was evident from the occurrence of chiastolite, augite, garnet, and felspar in sedimentary rocks. The presence of water chemically combined in the masses ejected by volcanoes was a proof that it played an important part in the phenomena that take place at great depths. He then referred to the facility with which minerals, and especially the silicates, can be formed when water is present, to Daubrée's production of Wollastonite, to his process of forming the anhydrous silicates in the moist way, and his production of a substance like mica and chlorite. Mr Livingston believed that these researches invite us to hesitate before we commit ourselves to the views of the igneous rocks at present in vogue, and expressed his conviction that the faith of geologists, after much weary tossing between fire and water, would finally settle down somewhere between these two extremes.

A conversation followed on the plutonic and aqueous agencies in the formation of rocks, and on the probable aqueous origin of granite, in which Professor M'Donald, Mr Alex. Bryson, and others, took part.

Wednesday, 24th April 1861.-ALEXANDER BRYSON, Esq., President, in the Chair.

The following gentlemen were balloted for, and elected non-resident members of the Society :

The Rev. George Gordon, LL.D., Manse of Birnie, Elgin; LieutenantColonel George Logan Home, K.L.H. and K.R.G., of Broom House and Edrom, Dunse.

The usual Committees were appointed for special investigations during the summer.

Memorial against Salmon Fisheries Act.—Mr GEORGE LOGAN, Convener of the Committee on Marine Zoology, read a memorial to the Lord Advocate, which had been prepared, praying for various alterations on his proposed Salmon Fisheries (Scotland) Act 1861, which, unless the prayer of the memorial was granted, would put a stop to a considerable part of the means used by the Committee in investigating marine zoology. The memorial was approved of, and powers were granted to the Committee to use its best endeavours to get the prayer of the memorial carried into effect.

The following donations to the Library were laid on the table, and thanks voted to the donors :

1. Proceedings of the Royal Society of London. Vol. X., 1859-60, and Part I. of Vol. XI.-From the Society. 2. Proceedings of the Academy of Natural Sciences of Philadelphia. 1860. 3. A Notice of the Origin, Progress, and Present Condition of the Academy of Natural Sciences at Philadelphia. By W. S. W. Ruschenberger, M.D. 1860. -From the Society. 4. The Quarterly Journal of the Geological Society. No. 64, November 1860, Vol. XVI., Part IV., and No. 65, February 1861, Vol. XVII., Part I.—From the Society.

I. Some Statements in Cuvier's "Natural History of Fishes," as to the Herring, shown to be erroneous. By J. M. MITCHELL, Esq.

Mr J. M. Mitchell stated that he had observed several errors in some of the principal works on natural history as to the herring, which he might afterwards more fully discuss; but in the meantime he would point out some erroneous statements in Baron Cuvier's "Histoire Naturelle des Poissons," edited by Professor Valenciennes. In the twentieth volume of the quarto edition, page 35, it is said, "that in the northern seas, as far as the White Sea, all the individuals have an

invariable largeness, always superior to that of our herrings of the Channel, of which the small dimensions are equally constant." Now, he said, it was true that considerable shoals of large herrings do appear on the Norway coast in the winter and spring; but the author seems not to have been aware that there is always in summer considerable shoals and a large fishery of small herrings, generally of a superior quality, but of a smaller size on the average than those caught in the English Channel (La Manche) or on the Scottish coasts; and he exhibited a specimen of each size, the one a giant of 13 inches, and the other a dwarf of about 9 inches, each with the ova fully developed, and said that any number of each size could be obtained. He alluded

to the statement in the same work as to the exceedingly deciduous nature of the scales of the herrings, and said that this was an exaggeration, as was evident even from the specimens he produced, which were covered with their scales. It is stated in this work, that the herring spawns apparently indiscriminately, without selecting any position, even in the middle of the sea-" au milieu de la mer." But this is not the case; for Mr Mitchell had ascertained that the herring always selects rocky, stony, or gravelly ground, on which to deposit its spawn. He would also point out that at page 62, vol. xx., it is said, "c'est pendant l'hiver qu'ils appairrissent sur les côtes d'Europe." Now, it is well known that great shoals of herrings approach the coasts of Europe in summer and autumn, and are fished then, as already stated, in great quantities.

II. Observations on British Zoophytes and Protozoa. By T. STRETHILL WRIGHT, M.D.

1. On the Reproductive Elements of the Rhizopoda. Plate IX. We have, as far as I am aware, no definite observations as to the reproductive elements of the Rhizopods. All who are accustomed to the observation of minute marine life know that these creatures increase with great rapidity; but how they increase is at present a mystery.

Professor Carpenter* has recorded and figured a peculiar *Phil. Trans., vol. cxlvi. p. 212.