6

As it was intended that the exploration in the Porcupine' in the summer of 1869 should occupy much more time, and if possible be much more thorough than that in the Lightning' the year before, the preparations for the Porcupine' expedition were much more elaborate and comprehensive. The Committee of the Royal Society were desirous that various important questions as to the physical condition and chemical composition of the water at great depths should be investigated; and the singular temperature results of the former cruise ably discussed by Dr. Carpenter in his preliminary report had excited so much curiosity and interest that their further elucidation was regarded as vieing in importance with that of the distribution and conditions of animal life. It was consequently decided that the naturalists directing the expedition should be accompanied by assistants trained in chemical and physical work, and the chartroom of the vessel was fitted up as a temporary laboratory, with physical and chemical apparatus and microscopes.

The vessel was available from the beginning of May to the middle of September, and as it was impossible for those who had conducted the previous expedition to be absent so long from their public duties, it was resolved to have three separate cruises; and Mr. Gwyn Jeffreys, F.R.S., whose co-operation was specially valuable from his thorough knowledge of the species and distribution of recent and fossil mollusca, was associated with Dr. Carpenter and myself, and undertook the scientific charge of the first cruise.

Mr. Gwyn Jeffreys was accompanied by Mr. W.

Lant Carpenter, B.Sc., as chemist and physicist; and during the first cruise they explored the west coast of Ireland, the Porcupine Bank, and the channel between Rockall and the coast of Scotland. It was originally arranged that the second expedition, under the charge of the writer with the assistance of Mr. Hunter, M.A., F.C.S., assistant in the Chemical Laboratory in Belfast, in the physical department, should take up the ground to the north of Rockall, leading northwards to the point where we had left off the year before; but subsequently, for reasons which will be explained hereafter, we altered our plan and took the second cruise in the Bay of Biscay. Dr. Carpenter took the direction of the last cruise, in which we carefully worked over the Lightning channel,' and checked our previous observations; Mr. P. Herbert Carpenter, our former companion in the Lightning,' doing the analyses of water, and determining the amount and composition of its contained air; while I went as supernumerary and made myself generally useful.

The special appliances and apparatus which were prepared under Dr. Carpenter's superintendence, after much consultation among experts in different departments, for carrying out the various investigations, will be described, each in its place, when describing the several methods of investigation and their general results.

For the management of the dredging operations two assistants were appointed on the recommendation of Mr. Gwyn Jeffreys,-Mr. Laughrin, of Polperro, an old coast-guard man and an associate of the Linnæan Society, for dredging and sifting; and Mr. B. S. Dodd, for picking out, cleaning, and storing the

specimens procured. Both remained with us the whole summer.

The first cruise of the Porcupine' under the scientific charge of Mr. Gwyn Jeffreys commenced on the 18th of May and ended on the 13th of July. It extended for a distance of about 450 miles along the Atlantic coasts of Ireland and Scotland, from Cape Clear to Rockall; and included Lough Swilly and Lough Foyle and the North Channel to Belfast.

The first dredgings were made about 40 miles off Valentia, in 110 fathoms water with a bottom of mud and sand. The result of this dredging gives a fair idea of the fauna of the 100-fathom line on the west coast of Ireland. The mollusca are mostly northern species, such as Neæra rostrata, SPRENGLER; Verticordia abyssicola, JEFFREYS; Dentalium abyssorum, SARS; Buccinum humphreysianum, Bennett; and Pleurotoma carinatum, BIVONA. Some however, as Ostrea cochlear, POLI; Aporrhaïs serresianus, MICHAUD; Murex lamellosus, CRISTOFORI and JAN; and Trochus granulatus, BORN,-are Mediterranean forms, and impart somewhat of a southern character to the assemblage. Cidaris papillata, LESKE; Echinus rarispina, G. O. SARS; E. elegans, D. and K.; Spatangus raschi, LovÉN; and several varieties of Caryophyllia borealis, FLEMING, were abundant : but these species seem to abound at a depth of from 100 to 200 fathoms from the Mediterranean to the North Cape.

After coaling at Galway they proceeded southwards, and as the weather was very rough and unpromising they dredged in shallow water, from 20 to 40 fathoms, in Dingle Bay and the next week, with improving

weather, off Valentia and between Valentia and Galway, at depths varying from 80 to 808 fathoms (Station 2), with a temperature at the latter depth of 5°.2 C. The general character of the fauna was that which we have hitherto been in the habit of regarding as Northern. Several interesting things were met with— Nucula tumidula, MALM.; Leda frigida,TORELL; Verticordia abyssicola, JEFFREYS; and Siphonodentalium quinquangulare, FORBES. Among the echinoderms a multitude of the large form of Echinus norve

FIG. 8.-Gonoplax rhomboides, FABRICIUS. Young. Twice the natural size. (No. 3.)

gicus, D. and K., which I am now inclined to regard, along with several of its allies, as a mere variety of E. flemingii, BALL; and the fine asterid already mentioned, Brisinga coronata, G. O. SARS. Some interesting crustaceans, including Gonoplax rhomboides, FAB. (Fig. 8), a well-known Mediterranean species, and a young specimen of Geryon tridens, KROYER (Fig. 9), a rare Scandinavian form, and the only known North European brachyurous crustacean

which had not previously been taken in the British

seas.

Here the Miller-Casella thermometers were tried for the first time and compared with those of the ordinary construction. The minimum recorded by one of the former was 5°2 C., while that recorded by one of the best ordinary instruments of the Hydrographic Office pattern was 7°-3 C. As this difference of 2° C. was almost exactly what the results of the experiment previously made had indicated as the effect

L

FIG. 9.—Geryon tridens, KROYER. Young. Twice the natural size. (No. 7.)

of a pressure of 1 ton on the square inch, which is about equal to the pressure of a column of sea-water of 800 fathoms, this close coincidence gave great confidence in the practical working of the protected instrument, a confidence which all subsequent experience has fully justified.

Mr. Gwyn Jeffreys and his companions next proceeded to examine the sea-bed between Galway and Porcupine Bank, a shoal discovered during one of