alternating thin seams of black clay. The seams of clay consist of the fine mud washed and deposited upon the bank during periods of calm. This process is continued in the present time. The seams of clay varied in thickness from one-eighth to half an inch. The thickest seams of clay were penetrated at the depths of 8 feet, 24 feet, 32 feet, and 46 feet respectively.

In the glass tube marked A are the shells, and fragments of shells and stones, which the pump brought up from 15 feet to 20 feet below the surface. They consist of the following species of Mollusca and one Echinoid, namely :—

Pebbles of Quartz, Felspar, Hornblende, and Porphyry.

In the glass tube marked B are the shells and fragments from 20 to 30 feet in depth, and from 30 to 40 feet respectively. They consist of the following species, namely:

B LOWER.

Pholas crispata, Linn.

Pectunculus glycimeris, Linn.

Montacuta bidentata, Mont.

Pecten varius, Linn.

Lima hians, Gmel.

Cardium echinatum, Linn.

I am indebted to Mr. Marrat for examining and naming these shells. In other bottles are samples of the gravel obtained from the bottom of the bore hole and from Hoylake respectively.

I have already stated that the surface of East Hoyle Bank, where the bore hole was made, is about 13 feet above the Old Dock Sill, and that it is covered with 8 feet of water at spring tides. Ten feet below the surface of the bank, therefore, means 18 feet below high water; 20 feet means 28 feet below water, and so on to the greatest depth attained at the surface of the boulder clay, namely, 53 feet 6 inches below the bank, or 61 feet 6 inches below high water.

The gravel which rests on the surface of the boulder clay seems to indicate a period of shallow water, receding nearly to dryness with the tide, as now prevails in the bottom of Hoylake, from which data we may infer that a change of level between land and sea, to the extent of more than 20 feet, has taken place since the deposition of the bed of gravel. This would indicate an interval of time far greater than any historical records we possess referring to these islands; and, therefore, the modern land surface, and fanciful pictures of cattle grazing upon it, can no longer be credited with accuracy as a historical fact.

Mr. T. J. MOORE, exhibited the following from among recent additions to the Free Public Museum :

The skull of a young Sea Otter (Enhydris), and a collec

tion of over fifty skins, etc., of Mammalia, chiefly Rodentia, Insectivora, and smaller Carnivora, from Wyoming Territory and California, presented by Mr. H. Heywood Jones.

A specimen of Bulwer's Fire-backed Pheasant (Lobiophasis Bulweri, Sclater), a recently described species from Borneo, remarkable for the enormously developed fleshy horns and wattles of lurid blue.

Selections from a collection of marine specimens, including Plagusia, or young stage of the Pleuronectid family (Turbot, etc.), in which the eye of the under side has not yet removed to the upper side, as in later stages; a young Sun-fish (Orthagoriscus), less than an inch in length; fine examples of Phyllosoma and Isopod Crustaceans, etc., collected and presented by Captain Cawne Warren, ship "Bedfordshire," Associate of the Society.

A specimen of the Oblong Sun-fish (Orthagoriscus truncatus), taken in the North Atlantic, Lat. 18° N., Long. 45° W., and presented by Captain Sutherland, ship "Importer." This fish is rare in collections, though occasionally taken in British seas.

The skull of an Eared Seal (Otaria?) from Callao, presented by Captain A. J. Cooper, Pacific Steam Navigation Co.'s service.

Living examples of Marine Mollusca, Pleurobranchus, Aplysia, etc.; also of Peachia (hastata?), collected at Holyhead Island by Mr. John Chard and James Woods for the Museum Aquaria.

The following communication was then read :

NOTES ON THE POLYPIDOM OR SKELETON OF THE HYDRACTINIIDÆ.

BY MR. T. HIGGIN, F.L. S.

I HAVE the pleasure to draw your attention this evening to two or three forms of Hydractiniide very little known at

present even amongst those persons who make a special study of the Hydrozoa. The only species of Hydractiniide which we find noticed in our Manuals of Zoology, or described in works more particularly devoted to observations on the Zoophytes, is the common one which encrusts the empty shells of the whelk (usually inhabited by a hermit crab), found all round our coasts. In Hincks's British Zoophytes, we find the soft parts of Hydractinia echinata, that is the animal, fully described and figured, but no details of the structure of the polypary, or skeleton, are given. Dr. Allman, however, gives full details both of the skeleton and the soft parts in his beautiful work on the Tubularian Hydroids, published by the Ray Society in 1872.

In the year following the publication of Dr. Allman's work, Mr. H. J. Carter found amongst the British Museum sponges, sent to him for examination, some specimens of Hydractinia echinata, one of which in particular attracted his attention, because the entire calcareous shell of the mollusk on which it had grown had been converted into the chitinous, or or horny skeleton, of the Zoophyte ; so that nothing remained of the shell but its form. The pagurus, or hermit crab, had remained in the shell during the whole of the time that this transformation had been going on. It had for many years previously been known that a species of sponge had the power of burrowing into shells, and even into limestone, and that another was often found converting the shells of mollusks into sponge, skeleton and substance, but it was quite new to science to find this extraordinary vital power possessed by a Zoophyte. Mr. Carter, therefore, communicated this fact in a paper published in the Annals and Magazine of Natural History, in 1873, accompanied by a plate shewing the structure of the polypary, at the same time describing a new species. He further called attention to the fact that the examination of

the skeletons of these specimens of Hydractinia, shewed that certain branched forms in the British Museum collection, which had been provisionally placed by Dr. J. E. Gray amongst the sponges, were in fact no sponges at all, but the skeletons of branching forms of Hydractinia. He then proposed a classification of the Hydractinidæ, separating them into three groups, namely, "Incrusting species," "Branched procumbent species," and "Branched erect species." We have before us this evening examples of each of these groups. The first is represented by Hydractinia echinata; the second by Ceratella procumbens, and another species; and the last by a very beautiful specimen of Chitina erecopsis, which has lately come into the possession of our Museum. We do not know that any other specimens of the branching forms exist, besides those in the Liverpool Museum and those in the British Museum collections. The Liverpool specimen of Chitina erecopsis is only half the size of the London one, but Mr. Carter says that it is more beautiful, and is in a much better state of preservation. Both specimens are from the same locality (New Zealand), and are from the collection of Dr. A. Sinclair. We thus find the Hydractiniidæ not only encrusting shells, but also growing from stems, branching out procumbently, or rising erect into bushy forms. It is much to be regretted that Mr. Carter did not add another plate to his paper in 1873, giving a figure of one of these branching forms, since the want of it has caused much of what he then wrote, and has since communicated, to be very little understood. Our diagrams give us the animal of Hydractinia echinata after Hincks, and a section of the polypary after Carter. The skeletons of all the forms known when Mr. Carter wrote in 1873, are of a chitinus or horny nature; but about a couple of years ago, Mr. Marrat brought to my notice some small shells obtained by dredging on the West Coast of Africa, which he had received from Mr. R. J.