In the Geological Magazine for 1906 a key of the published figures of the Cretaceous forms referable to the genus Entalophora was offered in the hope that by means of it the difficulties attendant on the determination of the species of this genus might be obviated.

The remains of Dinosaurian reptiles are very abundant in the Rocky Mountain region, especially in deposits of Jurassic age, and during the past ten years the author has made extensive collections of these fossils, as a basis for investigating the entire group. The results of this work will be included in several volumes, two of which are now well advanced towards completion, and will soon be published by the United States Geological Survey.

In the study of these reptiles, it was necessary to examine the European forms, and the author has now seen nearly every known specimen of importance. The object of the present paper is to give, in few words, some of the more obvious results of a comparison between these forms and those of America which he has investigated.

The criticisms which appeared in the January and February Numbers of the GEOLOGICAL MAGAZINE, on certain writings of mine, require some reply. It is obvious that when an author ventures in any way to question or remark upon the results of others, he must expect their opposition to his statements. I have to offer a general apology to all authors on whose writings I have ventured to make critical remarks in the “Annals of British Geology,” that I was unable to send them proofs of the articles before publication, as I hope to do in future, as long as the work is continued. In that way misunderstandings would be avoided. However, I must now proceed to business.

The publication in the last Quarterly Journal of the Geological Society of the most instructive paper by Messrs. S. V. Wood, jun., and F. W. Harmer, on the Later Tertiary Geology of East Anglia, and one by the latter author on the Kessingland Cliff-section, induces me to offer the following remarks, with the hope that my views may be considered by geologists who have made this question their study.

In the previous paper I ventured to trace the history of the Baltic back to the time when the latest of its raised beaches were laid down, and to show that it was then considerably larger in size, and that its waters were more salt than they are now, although they were even then brackish (see Map I, Pl. XIX).

This conclusion was derived mainly from an examination of the molluscan remains in the more recent shell-beds. It is confirmed by other evidence; thus, Munthe mentions the occurrence in the so-called Litorina beds of three species of Rhizopods, whose present and former distribution in the Baltic is shown in the following table:

Remains of Echinoderms are so rare in the Hartwell Clay of Buckinghamshire, and when found so fragmentary, that it may be worth while drawing attention to a small piece of an Echinoid test recently obtained from the Hartwell Brick-pit by Mr. Edwin Hollis, F.Z.S., curator of the Aylesbury Museum, and presented by him to the national collection (Brit. Mus., Geol. Dept., E 12241). The terminology of the following description is that defined on pages 59–65 of my “Triassic Echinoderms of Bakony”, Budapest, 1909.

Most geologists are aware that the Chalk of Antrim, although full of flints and fossils like those in the English Chalk, is a hard splintery limestone, known here as the “White Limestone.” Its induration is often attributed to the action of the basaltic covering which spreads over it, and the coincidence of the two things is certainly remarkable; but I think I can now show that they are not connected in the way of cause and effect.

Thin, subplanar or parallel-sided syntectonic quartz veins from the Hodgkinson Province, North Queensland, Australia contain mica inclusions that are identical to wallrock mica textures. These ghost textures can only be produced by incomplete replacement of the wallrock by quartz. The planar form of the veins indicates that there was a planar control on their formation. We propose that the veins formed around syntectonic fractures that localized silica micrometasomatism of the fracture wall. The formation of the veins can be explained by a model which involves fracture of the wallrock, reaction between the fracture wall and the ambient metamorphic fluid and eventual sealing of the fracture by precipitation from the fluid. The new vein is then a locus of further fracture. Replacement of wallrock micas occurs via a two-stage process where biotite is replaced by muscovite, which is in turn replaced by quartz. We propose the term crack–reaction to describe the resulting cyclic process because it can be compared with the crack–seal model of vein formation. Crack–seal and crack–reaction are different only in the relative amounts of metasomatism and precipitation that occur subsequent to fracture and can be envisaged as end members of a more general vein-forming process.

The exact and exhaustive study of the Quaternary terraces of the Somme, which we owe to Commont, may well serve as a starting point in any consideration of this subject. In its results it is not without its surprises, for we should scarcely expect to find, as we do, that the gravels which form the earliest deposits on each of the three lower terraces all contain the remains of a “warm” fauna; the third or highest of these terraces affording Elephas meridionalis, the first and second E. antiquus and its companion Hippopotamus. Associated with these faunas are flint implements of early types. Pre-Chelléan in the third terrace, typical Chelléan in the second, and Chelléan “evolué” in the first. No signs of a cold climate are to be discovered in any of these gravels until we reach that of the first terrace, where a newer gravel is to be seen invading the older and bringing with it Acheuléan implements and the mammoth.

Having paid but little attention to geological literature during the last two years, it was not until September, 1878, that I became aware of Mr. A. J. Jukes Browne's article in the GeologicalMagazine of August, 1877. In this article, amongst other matters, the author criticises very fairly the classification of the Upper Greensand and “Chloritic Marl,” so-called, as set forth in my paper on the Cretaceous Rocks of Beer Head. In justice to certain questions involved, I find myself compelled to reply to this criticism, and to say a few words besides respecting the Chloritic Marl and Upper Greensand.