A Controversy apperas to be carried on between geologists as to the causes of the excavation of valleys, and the degree in which marine denudation on the one hand, or the eroding power of rain and rivers on the other, have been concerned in the process. To this controversy Mr. D. Mackintosh has contributed two papers, in recent numbers of this Magazine. I am desirous of recalling to the recollection of its readers certain facts which demonstrate, beyond the possibility of doubt, how vast is the error of those writers who, like Mr. Mackintosh, speak of “the impotence of rain as a denuding agent.”

I Have been favoured by the Rev. Peter B. Brodie, M.A., F.G.S., with part of the lower jaw, including eight back teeth (Pl. X., Fig. 1, natural size), of a small mammal, nearly allied to Spalacotherium tricuspidens, Ow., and from the same formation and locality, viz., the Marly bed Upper Oolite, Purbeck, Dorsetshire.

In No. VI. of the “Quarterly Journal of Science” I gave a brief account of the Trigonia semiundulata, M'Coy, MS., which has been found in certain Tertiary strata in the Colonies of Victoria and South Austraila, and which had been named, but not described, by Professor M'Coy. This species differs altogether from the recent forms, and approaches very closely in its essential characters to the members of the group “costata”, characteristic of the Oolites. It was therefore remarked, in the communication referred to, that its occurrence in Tertiary strata in Australia added another link to the chain of evidence which connects the recent fauna of that region with the Oolitic fauna of Europe. But doubt may be expressed as to the exact value to be assigned to this similarity in facies between two faunæ so widely separated in time; and it is a fair question whether the discovery of this Trigonia does not diminish, rather than add to the apparent peculiarity of the existing Australian fauna.

Among the many beautiful fossils from the Silurian strata of Bohemia, obtained by M. J. Barrande, there have been discovered numerous detached spines, measuring from six seven inches in length, which, from their resembalance to the genus Leptocheles of M'Coy, have received the MS. name of Leptocheles Bohemicus (Barr).

I Should not have presumed to publish an opinion as to the geological position of the roacks of Casterton Low Fell without having examined the typical region of Coniston and Windermere, had not Mr. Woodward thought it desirable to notice the occurrence there of a species of Ceratiocaris and asked me to furnish him with a note on the bed from which I obtained it. Having therefore collected all the evidence I could in that Limited and complicated area, I now, with the permission of the Director of the Survery, send him some extracts from my notes, which may be of interest, as showing the character and relations of the rocks there seen.

Although many theories have been suggested to account for the formation of coal-beds, all of which agree in the vegatable origin of the coal itself, none have yet apperared which meet many of the difficulties which surround the subject of their origin, and probably they have been deposited under so many varying conditions that no one supposition would account for the difference in the constituents of the mineral, or for the mode of its formation in different localities. From the Stigmaria found in the underclay, in the great majority of cases, it seems fair to assume that the vegetation from which the coal above it was formed, grew where the coal is found, and there are other reasons for coming to the some conclusion in these cases, but in some places, where the underclay is wanting, this may be doubtful.

The Junction of the Chalk with the Lower Tertiaries is nearly always marked by the presence of green-coated flints; and in East Kent, where the Thanet Sands rest on the Chalk, numerous junction-sections are exposed, exhibiting the peculiarities which I now lay before you.