After referring to the paucity of information on the placental characters of the sloths, and to the various inferences which had been drawn by anatomists from Carus's figure of the placenta of Bradypus tridactylus, some holding that it was cotyledonary and non-deciduate, others that it might have intermingled with it maternal deciduous substance, the author proceeded to describe his dissection of the perfectly fresh gravid uterus of a specimen of a two-toed sloth. This specimen, which was presented to him by Dr David Ridpath, only possessed six cervical vertebrae, and was referred to the Cholœpus Hoffmanni of Peters.

After pointing out that the observations of Alessandrini, Rosenthal, Eschricht, and Barkow on the placentation of the seals had been limited to the determination of the form of the placenta, and to the more salient facts connected with the arrangement of the fœtal membranes, the author in this memoir proceeded to describe systematically the gravid uterus, the form and structure of the placenta, and the arrangement of the fœtal membranes of the grey seal, Halichœrus gryphus. He was indebted to Dr M'Bain and Captain Macdonald of the cruiser “Vigilant” for the opportunity of acquiring the gravid uterus of a recently killed specimen of this seal. The distribution of the utricular glands was described. The affinities between the placentation of the seals and the proper carnivora, more especially the common bitch, were pointed out.

The author showed to the Society a small entire specimen of the P. gladius, and next described, from a larger opened and dissected one, and from part of an adult fish, the spinal cord, the brain, the organs of the senses, and other parts of its nervous system. He illustrated his remarks by exhibiting four large drawings and nine smaller ones, including six microscopic views, explanatory of his description of the structure and disposition of the spino-cerebral axis, the encephalon as viewed from above and below, the ramifications of the encephalic nerves, and more particularly the structures subserving the senses of smell, sight, and hearing.

In April 1871, this Committee was appointed for two purposes—one to ascertain the districts in Scotland where boulders of interest were situated; the second, to point out such boulders as were deemed worthy of preservation, with a view to an application to the proprietors of the land on which they were situated, to have them preserved.

By the kindness of M. de Boisbaudran I have been enabled to experiment upon a specimen of nickel, very nearly pure. Its thermo-electric relations are exceedingly interesting, and are easily observed by employing palladium as the second metal in the circuit. The nickel line in the thermo-electric diagram presents nearly the same appearance as that of iron, but its peculiarities occur at much lower temperatures.

Since the date of our last communication, we have continued our investigations, with the following results:–

1. The light from a beam of uncondensed moonlight, though of weak intensity, and almost entirely free from heat rays, is still sufficient to alter the electro-motive power of the nerve and retina.

2. We have examined the phenomenon in the eyes of the following animals:—(1.) The common newt (Triton aquaticus). (2.) The gold-fish (Cyprinus auratus). (3.) The rockling (Motella vulgaris). (4.) The stickleback (Gasterosteus trachurus). (5.) The common edible crab (Cancer pagurus). (6.) The swimming crab (Portunus puber). (7.) The spider crab (Hyas coarctatus). (8.) The hermit crab (Pagurus Bernhardus), and (9.) The lobster (Homarus vulgaris).

In 1862 I communicated to the Society a notice of the ravages of the Limnoria terebrans on timber employed in engineering structures exposed to the action of the sea. In that communication I stated that African, English, and American oaks, mahogany, teak, beech, ash, elm, and the different varieties of pine, were found sooner or later to become a prey to the Limnoria. The special object of the notice was, however, to show that timber subjected to preservative processes did not long resist the attacks of the Limnoria, and, more especially, that thoroughly creosoted timber is readily perforated by it, and subsequent experience has fully shown that these statements were correct.

Dr Matthews Duncan recently asked me whether the flow of blood under given pressure would be affected by a considerable change of form of the section of a small vein or artery. It appeared obvious, from the well-known experiments of Poiseuille (which show that when the bore of a capillary tube of circular section is sufficiently small, the flow through it is as the fourth power of the diameter), that the flow through a capillary tube of elliptical section must be le^s than that through a circular tube of equal sectional area.

If we have two equations of the form

u and v are given as functions of ξ and η, or vice versâ. Here either u and v, or ξ and η, may be the ordinary Cartesian x and y, or any given functions of them.

A systematic investigation into the physiological action of ozone, so far as we are aware, has never been undertaken. Isolated observations have been made by many while engaged in the examination of its physical and chemical properties, which have chiefly tended to show that it acts as an irritant on the mucous membrane of the respiratory tract, and they have also observed the peculiar odour which it excites by its effect on the organ of smell, from which the name ozone originated. Beyond this little has been attempted.

The sulphine compounds discovered by v. Oefele, indicate that, notwithstanding the difference of atomicity, there exists an analogy between sulphur and nitrogen, these compounds corresponding to the salts of the ammonium bases, not only in chemical properties but also in physiological action.

The research, the results of which are communicated in this paper, was undertaken with the view of examining this analogy in some other directions.

It seemed reasonable to suppose that, as the nitrile bases, such as trimethylamine and strychnia unite with chloracetic acid to form compounds such as hydrochlorate of betaine and of glycolyl-strychnia, the sulphides of the alcohol radicals should act in a similar way. Experiments show that this is the case—bromacetic acid acting readily on sulphide of methyl to form a beautifully crystallised compound to which the authors give the name of hydrobromate of methyl-thetine. Analyses proved this substance to have the composition corresponding to the formula C4H9SBrO2 which is that of the sulphur analogue of the hydrobromate of betaine.

In the Quarterly Mathematical Journal for 1860, I gave a quaternion process for obtaining in a very simple manner, from Ampère's experimental data, his well-known expression for the mutual action between two elements of currents. As one of the data the assumption was made, after Ampère, that the action is a force whose direction is that of the line joining the middle points of the elements, i.e., it was assumed that the necessary equality of action and reaction holds, not merely for two closed circuits but, for each pair of elements of these circuits.

A determinant which has the elements lying outside the principal diagonal and the two bordering minor diagonals each equal to zero, and which has the elements of one of these minor diagonals each equal to negative unity, may be called a Continuant.

Impressions of the tracks of large birds from this locality have lately been objects of attraction to visitors to the museum at Wellington, New Zealand. To these Dr Hector, F.R.S., has affixed a label, stating that they are from the “Sea shore sand” at Poverty bay, a harbour on the east coast of the north island. “Sand rock” would have been a preferable term, as to most observers the description is calculated to convey the idea that these footprints are but of yesterday's date.

Seven fossils, all apparently belonging to the Pine tribe, and either to the same species, or to two closely allied to one another, have been uncovered since 1826 in the sandstone of Craigleith Quarry. Six are stems of great trees; and one is a longitudinally split section of a large branch, or possibly of another stem. Portions of all seven have been traced as still in existence, and have been subjected more or less to examination. Of one, the greatest of all, about 36 continuous feet, from 12 to 14 feet in girth, have been removed in large fragments to the British Museum, and will be pieced and erected there.