In a recent number of the Geological Magazine, Dec. V, Vol. III, March, 1906, p. 120, there is an article by Prof. E. H. L. Schwarz which deals with the thickness of ice-caps during the various Glacial periods. At the outset Professor Schwarz takes the data furnished by Captain Scott's narrative of the voyage of the “Discovery” as the main support of the physicists' contention that an ice-sheet cannot exceed 1,600 feet in thickness.

A Great difference of opinion seems to exist among geologists, not only in Britain but also in other countries, in regard to the supposed occurrence of warm Interglacial periods during the age of ice. Those who incline to the views propounded by Adhemar and Croll as to the causes which produced the extraordinary climate of that time naturally look for alternations of cold and warm periods.

The various views put forth prior to 1893 to account for the origin of Indian laterites have been clearly and sufficiently discussed in Oldham's edition of Medlicott & Blanford's Manual of the Geology of India (pp. 369 et seq.). Since that year the only contribution of importance to the literature of lateritic genesis in India is a paper by Mr. Thos. H. Holland, F.R.S., the present Director of the Indian Geological Survey, having for its text the conclusions of Bauer. In it the author suggested that laterite might owe its origin to “some lowly organism,” but no sufficient data were advanced in support of the suggestion. Bauer's specimens indicated a certain amount of dehydration in laterites, and this fact, together with the absence of hydration products from certain peridotites in Southern India, was deemed to indicate a general dehydration for the bauxitic laterites of the Deccan. The gibbsite (Al2 O3, 3 H2O) of laterite was supposed to be dehydrated to diaspore (A2 O3, H2O), and it was assumed that “this irregular loss of water is probably the cause of variation in bauxite.”

The town of Yass, N.S.W., is situated on the Southern Railway about 190 miles from Sydney. It is the centre of one of the most picturesque districts to be met with on the journey from Sydney to Melbourne. The surrounding country is a veritable geological and palæontological paradise for the collector, who may depend upon turning up some new and interesting specimens every trip he takes to the district. The town itself is built on the Upper Silurian rocks, which about two miles distant, at a bend in the Yass River known as Hatton's Corner, offer to the palæontologist one of the most prolific collecting-grounds in Australia. Amongst the first to investigate these rocks were the Rev. W. B. Clarke and Mr. C. Jenkins, whose work was followed by a survey in 1882 by the Mines Department. Further good work was done by Mr. John Mitchell whilst stationed in the district; but even at this late hour there is a large amount of interesting work awaiting completion.

Although many of the nodular bodies met with in sedimentary rocks which were formerly held to be concretions or simple aggregations of mineral matter have since been found to be due to the work of minute animals or plants, there is yet a more numerous class of true concretions which were undoubtedly formed by chemical reaction in the surrounding water and sediments; the resulting precipitation being often deposited upon nuclei of organic origin, as fish, woody fragments, or shells. Occasionally these nodules were of subsequent formation to the deposit in which they occur. In nodules which include organic remains, the segregation was accelerated by the partial decay of the included organic fragments.

The remains of a Palæoniscid fish from the Lower Carboniferous rocks of Flintshire, submitted to me by Mr. J. T. Stobbs, are unfortunately not sufficiently perfect to afford material for a complete diagnosis. The specimen shows the impressions of the outer surface of both mandibular rami and of the left maxilla, and beyond this we have only a mass of dislocated scales—the general form of the fish, the position of the fins, and the condition of the fin-rays being entirely lost.