In the arid region of the goldfields of Western Australia a knowledge of the conditions under which a search for water is most likely to be rewarded is of prime importance to the prospector who may find himself away from the beaten tracks. There is, in the summer, little hope of finding fresh water in the long narrow bands of goldbearing greenstone-schist that run from N.N.W. to S.S.E. through Western Australia, for both the surface and the deep-seated waters of this rock-formation are then salter than those of the sea. When unprovided with ‘condensers’ for the distillation of these waters, the prospector must therefore turn towards the neighbouring granitic areas, and search either for ‘soaks’ or for the remarkable ‘gnamma’ holes of the bare rocky ridges. The first and most reliable of these sources of fresh water—the ‘soaks’ —presents nothing abnormal and requires little description. They are found in the sandy hollows at the foot of granite slopes. A well is sunk in the sand, and the water is baled as it slowly percolates into the bottom of the hole. The supply may vary from a mere trickle to several hundred gallons in twenty-four hours, according to the catchment, to the season, and to the permeability of the sand that has protected the water from evaporation since it was collected in the rock-hollow.

Having read with great interest Mr. E. E. L. Dixon's remarks on the Radiolarian cherts of Gower in the November number of the Quarterly Journal of the Geological Society, I am tempted to offer some notes on the occurrence of similar rocks in the Malay Peninsula and Archipelago, where Radiolaria-bearing rocks are known to be widespread.

One of the most important additions recently made to the Gallery of Fossil Reptilia at the Natural History Museum, is a mounted skeleton of the highly specialized Ichthyosaur known as Ophthalmosaurus icenicus, Seeley. This reptile presents many. peculiarities, for the most part indicating a very high degree of adaptation for life in the open sea and for rapid movement through the water, probably sometimes at considerable depths. In fact, Ophthalmosaurus may be regarded as representing among the Reptilia the swiftly swimming toothed-whales among the Mammalia, and it is interesting to note that the similar mode of life in the two cases has produced in some respects similar modifications. Thus the front paddles are enlarged, the hind ones reduced; in whales the latter have disappeared altogether. Again, there was a large caudal fin, vertical in this case, and the head was elongated, the snout sharp, and the neck so short as to be practically non-existent. The enlargement of the fore-paddles is brought about by the presence of a very large pisiform bone, which together with the radius and ulna articulates with the humerus, thus forming a very broad base for the expanded terminal portion of the paddle. Another striking peculiarity is the great reduction of the dentition, the teeth in the adult being very small and confined to the front of the jaws. Baptanodon, an American form very closely allied to, if not identical with, Ophthalmosaurus, was for a long time regarded as toothless. This reduced dentition, so unlike what is usually found in members of the group, must indicate some considerable change in the nature of the food, but what this was is unknown.

It may be of interest to note the occurrence of a somewhat rare and interesting rock, named keratophyre, at two easily accessible localities in a district where it has been hitherto unknown—at Moel-y-Golfa, in the Breidden Hills, and in the Berwyn Hills.

The Breidden Hills.

Moel-y-Golfa was visited by me in 1899, and I collected a few specimens, which, however, remained unexamined until a few days ago when I needed one for teaching purposes. On examination of a thin section the plagioclase proved to be albite, idiomorphic and tabular in form, set in a matrix of chloritic decomposition products, doubtless the remains of pyroxene. The ratio of albite to pyroxene must have been about two or three to one. This composition is sufficient to place the rock in the keratophyre group, but confirmation was obtained by comparison with a slide of the well-known keratophyre of Hüttenrode, in the Harz, the rocks proving almost identical both in structure and composition. The determination of the felspar was made by Becke's bright line method, which proved its refractive index to be everywhere slightly lower than that of balsam.

Cumberland Bay Series: Upper Division.—This consists largely of hard, coarse, compacted crystal tuffs, dark-grey or black in hand specimens, and resembling coarse grey wackes. In thin section they contain fragments of trachytic lavas, and detached crystals of orthoclase and oligoclase in a paste of minutely crystalline material mixed with much indeterminate matter. Iron-ores and ferromagnesian minerals are rare. In some of the rocks andesitic and latitic fragments are dominant, and occasional fragments of yellowish glass enclosing euhedral orthoclase are seen. Many of the rocks have suffered some degree of scapolitization. The tuffs pass into siliceous grey wackes still with some recognizable volcanic material, and are interbedded with fine banded mudstones which appear to represent volcanic muds. Radiolaria have been recognized in these rocks as well as in the tuffs. The mudstones occasionally become somewhat laminated and pass into black shales. An imperfect cleavage traverses many of these rocks at a high angle to the bedding. These tuffs doubtless represent the interbedded ‘diabas - schalstein’ of Thürach.

Field, petrographic and chemical evidence from the cumulates of western Lilloise suggest a substantially higher level of exposure in the cumulus pile than is seen on the E side, due to relative subsistence of the western half of the intrusion. It is suggested that the subsistence started while both cumulus pile and the surrounding basalts were still hot and not fully consolidated. When, later, reactivation occurred, the rocks were in a more cohesive state and ‘syenitic’ magma was available for intrusion as discrete sheets and veins.

To investigate the problem of porosity of wind deposited sands a sample of sand similar to Libyan Desert sand was used for wind tunnel experiments. Average velocity of wind—Average Porosity Curve was obtained for the first time, proving that low wind velocity produces higher porosity than high wind velocity, and that the relationship obtained agrees with the laws governing “vertical” deposition of sands.

The occurrence of stout and stumpy crystals of biotite elongated parallel to the schistosity and showing askew cleavage is found to be due to rotation. The relation between rotation of biotite and deformation is described. Rotated biotite contains a higher amount of FeO, TiO2 and Al2O3 in comparison to the unrotated fresh and recrystallized biotite.

Having been lately at St. Davids, I made some observations in relation to the Porth-lisky granite or Dimetian of Dr. Hicks, which may be worth recording in the pages of the Geological Magazine.

Perhaps it may be well for me to state that previous to my examination I had no bias whatever in favour of any of the explanations of the geology of St. Davids which have been offered by Hicks, Geikie, or Blake.

The rocks composing Basutoland belong to the Stormberg Series of the Karroo System. They cover a much larger area than Basutoland, extending into the Orange River Colony on the west and north, on the south and east into Cape Colony and Natal, and, I am informed, across the Vaal into the Transvaal. The area is thus not less than 45,000 square miles. The whole of that part of the Orange River Colony known as “the Conquered Territory,” east of a line drawn from Thaba 'Nchu to Vrede, is occupied by the whole or portions of these rocks.