among other fossil remains, he discovered several fragments of bones of gigantic Chelonians, one of which rivalled in dimensions any of the recent or extinct species hitherto reported from the Mascarene and Galapagos Islands. The remains were found in conjunction with bones and teeth of the dwarf elephants and gigantic dormice; and whilst remains of the Proboscidians and Rodents were extremely abundant in certain rock-cavities he examined, and the Chelonians were also well represented, it was a noteworthy fact that no traces of large Carnivora were met with. This absence of the order, excepting the tooth of a small Canis, he supposed accounted for the presence of the large helpless tortoises, as obtained also in the Galapagos and Mascarene Islands.

The largest of the Chelonians rivalled in dimensions the Testudo elephantopus and Testudo ephippium, and showed some affinities with the latter, but was generally distinguishable from any recorded species from these islands by a marked robustness of the bones; on which account he proposes to name it Testudo robusta. A smaller species, distinguishable also, morphologically, from the preceding, he proposes to name after Admiral Spratt; whilst a few bones of a small freshwater tortoise were indistinguishable from the same parts of the Lutremys europea, which is still not uncommon in the south of Europe and in certain islands of the Mediterranean.

The author was inclined to believe that the Maltese-cavern fauna belonged to a late Pliocene rather than a Pleistocene period, such as that exhibited by the Sicilian caverns, to wit, the Caves of Palermo; and that, although the Hippopotamus Pentlandi and smaller forms are both represented in Malta, Sicily, and Crete, the absence of traces of the dwarf elephants and gigantic dormouse in the two latter situations, and the presence of the IIyana crocuta, Elephas antiquus, and large Felidæ in Sicily, seem to point to faunas of two different epochs. Indeed, in the case of the Maltese deposits, it would appear, in some instances at all events, that the animal remains of the fissures had been derived from older beds which were broken up during the submergence of the area. But as the Maltese rocks were Miocene and the uppermost had been supposed to indicate the presence of Pliocene Invertebrata, it was clear that the red soil and clay which formed the matrix in which the above animal remains were found, in the rock rents, could not be more ancient than a later Pliocene.

He strongly advocated further explorations of the islands of the Mediterranean in quest of fossil remains, and stated that there was still much to be done in Malta.

On the Arenaceous Foraminifera collected in the Valorous' Expedition. By Dr. W. B. CARPENTER, C.B., F.R.S.

Further Researches on the Nervous System of Antedon rosaccus (Comatula rosacea, Lamk.). By Dr. W. B. CARPENTER, C.B., F.R.S.

Remarks on the Anatomy of the Arms of the Crinoids.
By P. HERBERT CARPENTER, B.A.

On Delphinus albirostris. By D. J. CUNNINGHAM, M.D.

Experiments on the Formation and Growth of Artificial Silica Cells.
By Prof. FERDINAND COHN.

On Spontaneous Evolution and the Germ Theory. By N. CARMICHAEL, M.D.

The Biological Results of a Cruise in H.M.S.

Valorous' to Davis Strait in

1875. By J. GWYN JEFFREYS, LL.D., F.R.S.

A preliminary Report on this subject was presented to the Royal Society, and has been published in their Proceedings,' vol. xxv. p. 177. The author gave an account of the voyage (which was undertaken by him in consequence of an application made by the Council of the Society to the Admiralty) and of the biological results, more especially with respect to geographical distribution and geology. The author treated of the Mollusca; and Professors Allman and Duncan, Dr. M'Intosh, the Rev. A. M. Norman, Dr. Carpenter, and Professor Dickie contributed notices of other departments of the marine fauna and flora.

A Double Dilemma in Darwinism. By the Rev. F. O. MORRIS,

Notes on Oceanic Deposits and their Origin, based on Observations made on board II.M.S. Challenger.' By JOHN MURRAY.

On the new Cases in the Hunterian Museum. By Prof. J. YOUNG, M.D.

ANATOMY AND PHYSIOLOGY.

[For Dr. M'Kendrick's Address, see page 126.]

On the Development of the Proto-Vertebræ in Elasmobranchs. By F. M. BALFOUR, B.A., Fellow of Trinity College, Cambridge. The mesoblast in Elasmobranchs arises as two independent plates, each of which becomes divided into two layers, a somatic and a splanchnic. In the dorsal part of each plate a series of transverse slits arises, which serves to distinguish a dorsal or vertebral portion of the plate from a ventral or parietal. A cavity is next formed between the two layers of the plate, which is continued quite to the summit of the vertebral part. Still later the segmented vertebral part of each plate, with its enclosed cavity, becomes separated from the parietal part and forms the muscle-plates. Each of these is a somewhat rectangular body, formed of two layers, enclosing between them part of the original body-cavity. The inner of these two layers soon buds off cells to form the rudiments of the vertebral bodies, and itself is transformed into longitudinal muscles; the outer layer of the muscle-plate becomes converted into muscles at a considerably later period.

On the Changes in the Circulation which are induced when the Blood is expelled from the Limbs by Esmarch's Method. By H. G. BROOKE, B.A. (Lond.), and E. O. HOPWOOD, B.A. (Oxon).

The authors stated that the object of the experiments was to observe the pulse during and after the expulsion of blood from the limbs. Healthy young men were experimented on, and the experiments were made one or two hours after a light meal. The pulse was counted with the aid of a watch, and its form recorded by means of the sphygmograph. The person experimented on was stripped and recumbent. Normal pulse-rate and sphygmographic movements were recorded; and afterwards one leg was bandaged from below upwards. During bandaging, pulserate was observed, and immediately bandaging was complete further sphygmographic tracings were taken. This was repeated with the other leg. After a short time both bandages were suddenly let go, and at the same instant pulse-rate and sphygmographic movements were again recorded.

As the result of their observations, the authors state that-

1. During bandaging of the first lower limb, the pulse-rate increases, and afterwards (generally after a very short interval) falls to about the normal.

2. During bandaging of the second lower limb, the pulse again quickens its pace, returning almost to the normal, but sometimes remaining a few beats above the normal.

3. When both bandages are suddenly let go, there is at once a marked acceleration of pulse-rate, but of brief duration.

The authors point out the changes which bandaging and unbandaging must have upon the disposition of the blood in the circulating system. Thus, on bandaging, the arterial blood is driven from the limbs bandaged into the arterial system of the trunk, head and neck, and upper extremities, raising the pressure all over the system: while the venous blood, together with the lymph, are also driven into the rest of the body from the compressed limbs, but are only able to affect the pressure in the trunk, head, and neck, being excluded by valves from the upper extremities. Hence the general venous pressure will have a relatively larger increase than the general arterial pressure.

Again, on unbandaging, the arterial blood rushes down the lower limbs to fill the previously obliterated vessels, thus diminishing the general pressure of the arterial system; while no such reflux of the venous blood is possible on account of the interposed valves of the veins. Hence, while the arterial pressure is diminished suddenly, the venous remains, for the moment, as it was; that is to say, the general venous pressure will experience a relatively less diminution than the general arterial pressure.

Now, comparing the conditions on bandaging and unbandaging, it will be seen that, in both cases, the relative difference normally existing between arterial and venous pressures on the two sides of the heart is diminished, on bandaging by approximating the venous to the arterial pressure, on unbandaging by approximating the arterial to the venous pressure. May we not, the authors suggest, seek in this coincidence of conditions an explanation of the somewhat unexpected similarity of effect on bandaging the lower limbs and on loosing the bandages?

In the course of the discussion which followed, Professor Kronecker, of Leipzig, pointed out that the addition of a large quantity of lymph to the blood on bandaging, by altering the composition of the blood, might well be supposed to affect the heart's rate, since the heart is now known to be very sensitive to qualitative changes in the fluids bathing it.

On the Morphology and Histology of the Nervous System of Antedon rosaceus (Comatula rosacea, Lamk.). By Dr. W. B. CARPENTER, C.B., F.R.S.

On a Hypothesis of the perception of Articulate Speech. By Dr. CASSELLS.

On the Morphological Relations of the Lower End of the Humerus.
By Professor CLELAND, M.D., F.R.S.

In this communication it was pointed out that the torsion of the humerus spoken of by more than one writer has no existence in nature, and that the limb is developed in its morphological position. While the radius is morphologically anterior to the ulna, the anterior, posterior, external, and internal aspects of the humerus have morphological relations exactly corresponding with those names, so that the flattening of the lower end of the humerus is not a commencement of the expansion which results in two bones in the forearm. The radius does not belong to the outer side of the humerus, nor the ulna to the inner side; but the radius is in front of the humerus, the ulna behind it, and the limb is in its morphological position when the forearm is in semipronation.

On a Hydrocephalic Skull, and on the Duplicity of the Temporal Ridge. By Prof. CLELAND, F.R.S.

On the Spinal Nervous System of the Cetacea. By D. J. CUNNINGHAM, M.D., Senior Demonstrator of Anatomy, Edinburgh University.

At the outset of my investigations into the anatomy of the spinal nervous system of the Cetacea, I endeavoured to discover whether any anatomist had described the arrangement of these nerves. This was no easy matter, so little had been written on the subject. H. Rapp (Die Cetaceen,' Stuttgart, 1837) states that, "with respect to the course of the spinal nerves (of the Cetacea) there are no researches ;" and Stannius (Lehrbuch der Vergleichenden Anatomie,' Zweiten Theil, 1846, p. 393) simply mentions that "in the Dolphin a nerve-trunk proceeds out of the lumbar plexus, the branches of which are intended for the muscles of the rudimentary pelvis, and for the external genital organs and their muscles, as well as for the region of the anus." Indeed it was not until I had finished my investigation that I discovered that Swan, in the "Table of Contents" or Introduction to his work upon the Comparative Anatomy of the Nervous System,' published in 1835, gives a short account of the whole nervous system of the porpoise. I believe, however, that besides extending his account very materially, I am able to give additional results; and I have taken care to have all my dissections illustrated by drawings, whilst he, with his wealth of plates of the nervous system of other animals, does not give one of the nervous system of the Cetacea.

I may mention that the following results are derived from the dissection of four members of the Cetacean group, viz. three porpoises and one dolphin*.

Spinal Cord.-The spinal cord is surrounded and supported on all sides by the dense rete mirabile, which may be looked upon as performing a threefold function: (1) it constitutes a soft pliable packing material, by means of which the cord is protected from shocks; (2) it maintains a uniform warmth around this important and delicate nervous centre by keeping it constantly bathed, as it were, in warm arterial blood; (3) and lastly, as Professor Turner has pointed out (Trans. Roy. Soc. Edinb. vol. xxvi. p. 233), it subdivides the arterial stream, and equalizes its force before it reaches the brain and spinal cord.

In the porpoise the spinal cord extends from the margin of the foramen magnum to a point corresponding to the interval between the 6th and 7th lumbo-caudal vertebræ, and opposite to the foramina of exit of the 27th pair of spinal nerves. It presents two enlargements-one in the cervical, and the other in the lumbar region. The former of these is connected with the nerves which go to form the cervical and brachial plexuses, and the latter with the nerves which supply the genital organs and the muscular apparatus of the tail. Between these enlargements the cord is of uniform diameter, and the lumbar swelling tapers away in a fusiform manner into the filum terminale.

Roots of the Spinal Nerves.-The direction and length of the nerve-roots and the size and position of the ganglia vary in the different regions of the spine.

The nerve-roots which proceed from the cervical and lumbar enlargements of the cord are closely crowded together, whilst in the dorsal region they are placed at considerable intervals from each other. Those arising from the lumbar swelling are very long, tortuous, or curly, loosely bound together by lax connective tissue, and they constitute the cauda equina. They pass directly backwards to reach their respective foramina of exit. The dorsal and cervical nerve-roots are much shorter, and the former are directed outwards and backwards, whilst the latter, with the exception of the first three which pass directly outwards, take a course outwards and forwards.

In all the regions the superior nerve-roots are smaller than the inferior-thus constituting a marked contrast to most mammals, in which the reverse of this arrangement holds good. Nowhere, however, is this difference in size so marked as in the cauda equina, in the last nerves of which the superior root is half the size * A young specimen of D. albirostris (vide Proc. Zool. Soc. 1876, p. 679).

of the inferior, and in some places so delicate that when stripped of the loose connective tissue which surrounds it, it resembles (in the porpoise) a fine thread or hair. From this fact we must not conclude that sentiency is dull in the Cetacea, for as the animal tapers towards the tail, the amount of skin to be supplied with sentient fibres is small in comparison to the huge muscular masses to be supplied with motor filaments. In the cervical, dorsal, and upper lumbar regions, where the cutaneous surface is extensive, the superior roots attain a size only slightly smaller than the inferior roots.

Spinal Nerves. In the lumbo-caudal region of the vertebral column of a porpoise or other cetacean, the intervertebral foramina correspond to the intervals between the laminae of contiguous vertebræ, and consequently lie on a higher horizontal plane than the transverse processes. As we approach the dorsal region, however, a rudimentary pedicle begins to show itself, and this becomes more and more marked as we pass on towards the cervical region. In the cervical and dorsal regions, therefore, the intervertebral foramina occupy a more ventral plane, being situated between the pedicles and inferior to the transverse processes. It follows from this that the removal of the great extensor muscle in the lumbo-caudal region displays the whole spinal nerve issuing from the spinal canal, whilst in the dorsal and cervical regions it only exposes the superior divisions of these nerves passing upwards between the pedicles.

Cervical Nerves.-These are eight in number, and, owing to the fusion or close opposition of the vertebræ in this region, they are closely crowded together. Each nerve divides into a superior and inferior division. The superior divisions supply the muscle and skin on the superior aspect of the neck, and are in some cases (e. g. dolphin) joined together by communicating branches which lie close to the vertebræ. The first three of the inferior divisions join together, so as to form a cervical plexus, whilst the remaining five, together with the first dorsal nerve, and in some cases a small twig from the second dorsal nerve, enter into the formation of the branchial plexus. The chief branches of the branchial plexus are those which correspond to the musculo-spiral, median, and ulnar nerves in man. There is no circumflex

nerve.

Dorsal Nerves.—The superior divisions of these nerves join together in a plexiform manner. Well-marked communicating branches pass between the various superior trunks, and connect them with each other. A longitudinal cord or plexus is consequently formed. The distribution of the inferior divisions is similar to that of the same nerves in other mammals.

Lumbo-caudal Nerves.-The arrangement of the spinal nerves posterior to the dorsal region is different from that of any other group of mammals (excepting perhaps the Sirenia) with which I am acquainted. The final cause of this is obvious; it is an adaptation of the nervous system to suit peculiarities in the muscular construction of these animals. In other mammals powerful inferior extremities are developed for the purpose of locomotion, and consequently the inferior divisions of the lumbar and sacral nerves are large as compared with the superior divisions, and they are thrown into plexuses to supply the muscles which act upon these limbs. In the Cetacea, on the other hand, lower limbs are absent so far as locomotion is concerned. The tail is the great organ of progression, and the muscles which work it are developed equally above and below the transverse processes of the vertebral column. In consequence of this, the superior divisions of the spinal nerves have as important a part to play in the supply of the muscles of the chief organ of locomotion as the inferior, seeing that it falls to them to give branches to the extensor muscles, whilst the latter have as their office the supply of the flexor muscles. The result of this is, that the superior and inferior divisions of the lumbo-caudal nerves in the Cetacea are very nearly of equal size. To insure the proper nervous supply of the four great muscular masses which work the tail, two great longitudinal cords or trunks are formed by the spinal nerves on each side of the vertebral column-one superior, and formed by the junction of the various superior divisions, and the other inferior, and formed by the union of the inferior divisions. The first of these commences towards the middle of the dorsal region; but even in the cervical region a tendency to a similar arrangement is exhibited. The inferior longitudinal cord begins further back, at a point corresponding to the