The recent discovery in the Woodwardian Museum of an undescribed species of Isopod from the Upper Greensand of Cambridge affords an opportunity for the revision of the entire list of that class of fossils. The total number of species which have hitherto been described as occurring in a fossil state is inconsiderable, —probably scarcely thirty—including both foreign and British. To what extent this small number expresses the variety of specific form of this tribe of Crustaceans, which actually existed during the period of deposition of the several rocks in which their remains occur, it is impossible to determine, as doubtless by far the greater proportion of the individuals perished by reason of the delicacy of their tissues—the larger and thick-shelled species only having been preserved—the small, thin-shelled kinds not admitting of recognizable “fossilization.” Specimens of Jurassic and Cretaceous Isopods are very rare both as to variety and individual number, and it may be inferred that this rarity of occurrence results from the more or less turbulent conditions under which these marine deposits were formed. The Tertiary estuarine and freshwater species, buried under more tranquil conditions, are much better preserved, and occur in some localities in innumerable abundance—Sphœroma, Archœoniscus, etc.

The specimens of pisolite which I have examined were obtained from two horizons, namely, the Coralline Oolite and base of the Inferior Oolite near Cheltenham. The pisolites are well known and have frequently been referred to by authors as fine types of oolitic granules, and in proof of this I may quote from Mr. H. B. Woodward's last edition of his Geology of England and Wales. Speaking of oolite granules the author says (p. 281), “ When these particles approach the size of a pea or bean, the rock is termed Pisolite, Pisolitic Limestone, or Pea-grit.”

In a former communication (Geol. Mag. Dec. III. Vol. IV. No. 9, p. 396, 1887), when pointing out how Reinecke's Amm. serpentinus had been misunderstood, I gave as a synonym, but with a query, Sowerby's Amm. Strangewaysi. As I have, since then, examined the type-specimen of the latter species contained in the collection of the Natural History Museum, and as Mr. E. Walford kindly forwarded me for my determination a capital specimen from Byfield, I have been able to satisfactorily settle the identity of these forms. Except being evolute carinate Ammonites, the two species have hardly a feature in common.

Discoidal, compressed, hollow-carinate. Whorls flattened, ornamented with genuine sickle-shaped ribs, which, though less conspicuous in size on the body-chamber, are there more distinctly bent. Ventral area marked by the prolonged forward sweep of the ribs, and surmounted by a well-marked hollow-carina.

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.

Some three years ago the writer communicated to this Magazine a “ Note on the Genus Stenotheca ” of Hicks, stating that from the appearance of the species, which on this (western) side of the Atlantic had been referred to it, it did not seem to belong to the Pteropoda, but more probably to the Gasteropoda. I also stated that there were two distinct types of shells which had been referred to Stenotheca, one of which by its internal muscular scar and position of the umbo might be compared to Parmophorus, etc.; while the other, represented by a number of minute species, appeared to correspond to the original Stenotheca of Dr. Hicks.

A Paper on the Glaciation of Eastern Canada by the writer will shortly appear in the Canadian Record of Science, Montreal. It is intended to be a condensed statement of the principal facts hitherto collected on this interesting subject, with references to the reports and publications in which details are given. The following is an abstract which I send to the Geological Magazine in advance. The subject is regarded as an important one, and has occupied the attention of geologists for many years, as Eastern Canada is the battle ground, so to speak, of the advocates of the rival theories of continental glaciation and floating ice. The results thus far obtained from a somewhat careful study of its glacial phenomena, however, point to conclusions which are at variance with those held by extreme glacialists, and show that the theory of local glaciers upon the more elevated portions of the country and icebergs or floating ice striating the lower coastal areas during the Post-Tertiary submergence of these, as maintained by Sir William Dawson, will serve to explain all the observed phenomena.

The mineral ottrelite, which has received so much attention elsewhere, especially in the Ardennes, and which is of considerable interest in connection with the metamorphism of certain rocks, has not, up to now, ever been reported as occurring anywhere in Great Britain.

I am able to state that I have discovered it in considerable amount in a certain roofing-slate of North Cornwall.

As early as the times of Descrates (1668) and Newton (1681), the “ settling and shrinking of the whole globe after the upper regions or surface began to be hard,”2 was held a sufficient cause for the formation of mountain-chains. Following the growth of our knowledge of mountain-structure, the contraction theory has been rediscovered several times in the present century. It has been worked out in great detail by Élie de Beaumont, Prevost, Delabeche and others; but, above all, by J. D. Dana, the real founder of the theory, in an admirable series of papers extending over the last forty-two years.

Leaving its details out of account, the fundamental idea in the contraction theory may be stated as follows: The whole earth was originally at a high temperature throughout, its present distribution of temperature being the result of cooling since the initial epoch.

Some very interesting deposits of Pleistocene age have lately been exposed on the Burton Road, Derby. The road rises on the north side of Mill Hill, and near the top, at the height of 260 feet, cuts into a mass of Boulder-clay, which is, or was, well shown in the cuttings for the new roads leading into Byron Street. Another outlier of the same clay is exposed in Littleover Lane to the southwest. The main mass of the deposit cut into on the Burton Road is a red morainic clay with boulders; apparently a subaerial moraine subsequently modified by the passage over it of land ice. Unlike the tough, silty, red and blue aqueous Boulder Clays so plentifully spread over the Midland counties, it shows little or no signs of aqueous action. Sometimes it has a banded or streaked appearance, but this seems to be due rather to a crushing or pressing-out action than to original conditions of deposition.