The special features of interest attaching to the Tertiary igneous rocks of Mull have been made known to geologists mainly through the classic descriptions of Professor J. W. Judd and Sir Archibald Geikie. The point of view of these two investigators is, however, essentially geological, and they refer but little to the occurrence of minerals and rarely give precise localities. It is clear, too, that the late Professor M. F. Heddle did not make an exhaustive examination of many localities in Mull, for his collection in the Royal Scottish Museum contains very few specimens from that island. With a view to filling up this gap I have paid several visits to Mull, and this paper deals with some of the material which I collected. The officers of the Geological Survey who are at present mapping the island have helped me considerably with information and material; and to Mr J. B. Richey, B.A., who has surveyed the area from which a large part of the material was obtained, I am particularly indebted for assistance in collecting specimens from somewhat inaccessible localities.

Depuis la publication de mon mémoire sur les Spongiaires de V Expedition antarctique nationale écossaise (9), j'ai reçu de M. le Dr. W. S. Bruce quelques Eponges antarctiques faisant aussi partie des collections de la Scotia mais dont le triage s'était trouve retardé.

Indépendamment de fragments en double d'espèces mentionées dans mon mémoire, ce second lot contenait plusieurs formes qu'il me paraît utile de signaler ou de décrire.

The specimens which form the subject of this paper were collected on voyages to and from Australia on board the s.s. Orsova and Otway of the Orient Line. Sea-water was being constantly pumped on each ship, by a rotary pump, from an inlet about 18 feet below the water-line to a large tank on the boat deck, and I was allowed to run off, through a plankton net, as much of the water as I desired in order to collect the organisms contained therein. For this privilege, of which I availed myself to a liberal extent, I beg to thank Captain J. F. Healey and Captain F. S. Symons. The small organisms suffered comparatively little by their passage through the pump and pipes, and were, for the most part, in a living and active condition when examined.

After my return from my first voyage, namely, the Scottish Antarctic Expedition of 1892–93, for which I was chosen as naturalist, I had the advantage of coming closely in touch with Mr J. Y. Buchanan, who then trained me in his Edinburgh laboratory in the use of his hydrometer. During the past twenty years I have been in constant touch with him regarding problems relating to the physics of the ocean. As a consequence, before my departure for a voyage to, and wintering in, Franz Josef Land during 1896–97, I was well trained in the use of his hydrometer, and obtained during that expedition observations of considerable interest. I also carried out all the hydrometer work on board the Prince of Monaco's yacht Princess Alice during his Arctic voyage of 1898, under the direction of Mr J. Y. Buchanan, who was also on board during that cruise, and also during the Prince of Monaco's second Arctic cruise during 1899, when I was solely responsible for that work. Consequently, I was thoroughly familiar with hydrometer work when I set sail in the Scotia.

In Part I of a Memoir “On the Craniology of the People of Scotland,” published in the Transactions of the Society twelve years ago (vol. xl), I described the anatomical characters of 176 skulls, the majority of which had been obtained in the counties south of the Clyde and the Tay. The dimensions, form and proportions of the cranial box and of the face were examined, the cranial and facial indices were computed, several of the skulls were figured from the vertex, lateral aspect and face, and mesial sagittal sections of the skulls with radial and other measurements were reproduced. The Memoir gave the fullest account of the characters of the skulls of the modern Scottish people which had been produced up to that time. In the concluding paragraph I stated that I had formed a collection of skulls of the prehistoric in-habitants of Scotland, which I proposed to describe to the Society in Part II of the Memoir, and to discuss the general ethnographical relations of the Scottish people. From various causes the presentation to the Society of this Part has been too long delayed.

Hitherto there has been described only a single species—Dicoryne conferta (Alder)—amongst the Hydrozoa in which the reproductive body is a sporosac which becomes ciliated and free-swimming. We have found that another species which, as we shall show (pp. 269–271), must be named Dicoryne conybearei gives rise to reproductive bodies of this type, which, however, differ from those of Dicoryne conferta in several important respects. The free-swimming type of sporosac has not been the subject of close observation since 1872; we have therefore made as complete a study of the structure and development of the sporosacs, especially of D. conybearei, as material gathered from several sources would permit.