In the summer of 1891 a journey was undertaken by the writer to the S.W. Governments of Russia, the immediate object in view being the study of the geology of that region. This portion of the notes then taken will deal more especially with the extent, thickness, and general contour of the Cretaceous beds of the district, together with a review of the Eussian literature bearing on the zonal distribution in the various Governments.

In 1845 Murchison had gathered together most of the facts then known regarding the Cretaceous formation of S. Russia, but his own direct observations were few, and the work was considered of only secondary importance. Under these circumstances it would not have been very surprising to find that he had fallen into error on many points.

Having sifted the evidence in so far as it is available in Scotland and the North of England, we will now advance further south; and first in regard to the Eastern Counties. Here as elsewhere it is unfortunate that we so very seldom can find the beds upon which the solution of the problem depends in actualcontact so as to apply the only real test, namely, that of superposition. When we can do so, it seems to me the case is conclusive.

It is not impossible that readers of a paper lately published by our venerated senior geologist may have been startled, some for one reason others for another and opposite. On reading the suggestions he has put forward as to the results from rapid elevations over southern England, some will recoil as at a revival of catastrophic machinery; some on the other hand may hail the invention of anovel and most potent agency. I doubt whether either view is altogether correct or defensible.

In the south-west of the Lleyn peninsula, the country inland is generally covered by drift, but the Survey map marks some isolated patches of rock as “Serpentine.” When I first visited the district, with the kind encouragement of Professor Bonney, under whom I was continuing my work at University College, I made a collection of these so-called “Serpentines” from ten different localities. The one at Porth din lleyn had been shown by Professor Bonney to be mainly diabase, and others of the examples have been since described in a previous number of this Magazine and elsewhere, but we have yet no complete account. I have, therefore, attempted to give a short summary, as preliminary to some discussion of the district.