In the volume of this Magazine for the year 1909 (p. 385) Miss D. M. A. Bate gave a short account with some figures of a remarkably modified goat-like ruminant discovered in some remnants of cave-deposits in Majorca.1 The chief peculiarities of this curious creature are that (1) instead of possessing the three pairsof incisors and pair of canines in the lower jaw, usual in the group,only the median pair of incisors remains, and these teeth are modifiedto form large permanently growing teeth like the incisors of arodent; (2) the cannon bones on both the front and hind foot areextraordinarily shortened, this being especially marked in the former.

In exercising a debater's right to reply to criticism, I shall be extremely brief. My contentions, in two essays on the above subject,1 were as follows:—

1. That the classification of rocks by silica percentage is unsatis-factory, and that a more natural basis for classification is available in the degree of saturation of the constituent minerals.

My critic, Mr. Scott, has not expressed any opinion on this pointof comparison.

2. That the field evidence is overwhelmingly favourable to the separation of the rock minerals into two groups, those of one group being stable in the presence of free silica under magmatic conditions, those of the other group unstable; and that such experimental work as has been done supports that separation.

This Plesiosaur was collected from the Oxford Clay at Peterborough by A. N. Leeds, Esq., F.G.S., and was acquired for the Hunterian Museum, Glasgow University, by Professor J. W. Gregory. The specimen has many striking resemblances to Cryptocleidus oxoniensis, but detailed examination showed that it could not belong to that species, and the differences existing in the paddle, shoulder-girdle, number of vertebræ, and conditions of ossification are such that it cannot be retained in that genus as now defined. The paddle closely resembles that of Tricleidus, but the shoulder-girdle alone is sufficient to prevent the inclusion of the specimen in that genus. It seems advisable to create a new genus, and as it may be some time beforea full description can be published a preliminary account is here given.

In the preceding paper I dealt with the five principal and zonal sub-Alpine lake basins in relation to their age and origin, while the object of the present one is to group and consider the more prominent of the smaller Swiss lakes which I have had repeatedly occasion to visit and examine. Omitting the high altitude lakes, such as the Merjelen and the Engadine Lakes, which I described in previous papers, as also the hundreds of lakelets disseminated throughout Switzerland, I shall confine myself to those lake basins from whose glacial or hydrographic features definite conclusions may be drawn. The illustrations (Sheets Nos. 1–4, Figs. I–X), having to cover the large area of Central and Northern Switzerland, are necessarily drawn to a small scale, but all particulars may be gleaned from the Swiss 1 : 25,000 contour map, to which the metric altitudes and dimensions in this paper correspond.

An important factor in the formation of this drainage area as above outlined is the movement of the rocks after they had been reduced to a surface comparable with a peneplain. These movements are now reviewed to see if any assumptions have been made which are probably incorrect from stratigraphical evidence.

The chemical composition of the Barshaw bekinkinite has been determined by Mr. E. G. Radley, of the Geological Survey (Table I). In the Glasgow Memoir (pp. 134–5) Mr. Bailey points out the general similarity of this analysis to those of picrite, nepheline-basalt, and Hillhouse basalt, from the Lower Carboniferous of the Midland Valley of Scotland, and also to the type bekinkinites of Madagascar.The Barshaw rock, however, is distinctly richer in lime and alumina than the other Scottish rocks, indicating a greater richness in the anorthite molecule. This is well brought out in the calculation of the mineral composition from the chemical analysis (see later). The ultrabasic end-differentiates of the Scottish analcite rocks tend either to be enriched in the bisilicate minerals or in olivine. The former type includes the Barshaw bekinkinite, the picrites, and some Ayrshire theralites; the latter includes peridotites, kylites, and certain nepheline- and analcite-basalts. Chemically the bisilicate type tends to be rich, in lime and ferrous iron, and comparatively poor in magnesia, with, for the silica percentage, a rather large amount of alkalies. The olivinic types are rich in magnesia, with low silica and alkalies. In the American Quantitative Classification the Barshaw bekinkinite falls into the subrang III, 6.4.5 (named ‘papenoose’ by Lacroix), whereas the bekinkinites of Madagascar fall into the neighbouring eubrangs III, 6.3.4 (limburgose) and III, 6.3.5 (unnamed). The majority of the Scottish analcite rocks fall into limburgose (III, 6.3.4), monchiquose (III, 6.2.4), or camptonose (III, 5.3.4), subrangs whose clear relationships are shown by their numerical symbols.

Olivine Ulrichite. — Megascopically this rock differs from the foregoing nepheline monchiquite in having a well-marked porphyritie structure, the phenocrysts including orthoclase and nepheline in crystals having a maximum dimension of nearly a centimetre. Under the microscope the minerals present are :—