Dr. Croll's “Climate and Time” is perhaps the most important geological work that has appeared in recent years, certainly the most valuable and original that refers to Glacial Geology. It teems with novel and instructive ideas. The part which is best known and has chiefly contributed to its celebrity is the theory, propounded and maintained in the first four chapters, of the causes of the Glacial Epoch. Though the theory met with much opposition at first, it seems now to be gradually gaining belief. Not only are Dr. Croll's views accepted by geologists, but his arguments are quoted in text-books. Now, when Science is used as a means of education, it is of high importance that the reasoning placed before the student should be sound. I propose in this article to examine Dr. Croll's description of the manner in which, according to his views, Glacial Periods have been brought about, to discuss the soundness of his reasoning, and to investigate the actions of the causes which he suggests. Some of the remarks here made are probably originally derived from an able article by Mr. S. V. Wood, jun., in the Geol. Mag. for 1876. The suggestion at the end of the paper is due to Mr. W. M. Hicks, M.A., Fellow of St. John's College.

The earliest attempt to describe the component beds of the English Chalk was made by W. Phillips in 1819: this is his well-known account of the cliffs between Dover and Folkestone, which is reproduced in Conybeare and Phillips' Geology (1822). He recognizes four divisions as follows:—

The subject of the recurrence of phenomena in geological time, so prominently brought forward by Prof. Ramsay in his recent address as President of the British Association, is one which cannot fail to be of interest to the geologist, as it constantly presents itself to him in all his inquiries. There are also doubtless many who are prepared to go with Prof. Ramsay to the length of his conclusions, and who believe “that from the Laurentian epoch down to the present day, all the physical events in the history of the earth have varied neither in kind nor in intensity from those which we now have experienced;” whilst others will be inclined to believe that though generally they have resembled one another in kind, yet that some have varied greatly in their intensity.

The name serpentine has been applied by many authors with so much vagueness that it appears to me desirable to lose no opportunity of examining any rock bearing this title, and to record briefly the result. A considerable number of patches of serpentine, generally of limited extent, are laid down on Ritter von Hauer’s Map of the Eastern part of the Alps, some of which also appear on that of Professor Theobald (sheet xx. of the Federal Map of Switzerland). Several of these I was able to examine, sufficiently for my purpose, during a visit to the district last summer.

Sp. char.—Tube small, sinistral, narrow, increasing but little in size towards the aperture, very narrow and fine towards the apex; volutions not in the same plane, somewhat raised, with a sunken apex, rather deeply umbilicated on the attached side; section circular. Surface marked with faint, regular, equidistant, transverse ridges, which are more marked along the union of the whorls (or “suture”) than on the periphery or back of the last volution.

In a previous paper we have considered some of the legends which are current among the Nomades of Siberia about the Mammoth, and which were the outcome of the curious fact that whole carcases of the animal have been discovered intact and with their soft parts and external shape preserved. This fact has not only been fruitful in romance among the inhabitants of the Tundras, and among those who are attracted by strange and unusual occurrences among more civilized people, but is in itself the key to a great deal of difficulty in understanding the later changes that have occurred in the northern hemisphere.

The following appear to be well-marked varieties of Microconchus pusillus.

1a.—Spirorbis (Micro.) pusillus, Martin, var. simplex, var. nov. (Plate VII. Fig. 8.)

Var. char.—The coil of the tube is open, lax, and imperfect, representing only a portion of the more developed coil; surface striæ very fine.

A Portion of the district referred to in this paper was described by me in a communication to the Geological Society, on May 22nd, 1878, and this was afterwards published in the Quart. Journ. Geol. Soc. vol. xxxiv. In that paper, however, many of the facts which had led me to the conclusions stated therein had to be omitted, and the important evidence derived from the microscopical examination of the rocks was hardly touched upon. It was then intended that this evidence should be given in an appendix to the paper, but, unfortunately, circumstances at the time prevented it.

Diabase-porphyrite—from hill designated as a Trigonometrical Station 1½ mile N.N.E. from Pwllheli: the hill is quarried for road metal; a good hand-specimen is easily obtained; it has a dark-green ground with porphyritic felspars up to ¼ inch long of pale greenish colour; a little pyrites; very slight effervescence with acids.

The evidence relating to the habitation in England at some distant period of a species of the section of the genus Felis represented by the Lynx, rests, up to the present time, upon a portion of a skull and a ramus of a mandible, which were discovered in a cavernous fissure in rocks of Permian age, in Pleasley Vale, Derbyshire. They were found by Dr. Ransom, who communicated an interesting paper descriptive of the fissure and its contents, to the British Association Meeting held at Nottingham in 1866, and the fragments were then referred to the Lynx of Northern Asia (Felis cervaria). Subsequently they were examined by Professor Boyd Dawkins, who, after carefully comparing the skull, jaw, and teeth, with the corresponding parts of other species of Lynxes, and also taking into consideration its geographical range, says, “that they may be referred with equal justice to the Lynx of Norway and Sweden” (Felis borealis).

The first part of the “Records of the Geological Survey of India” for 1879 contains some interesting notes by Mr. R. Lydekker, B.A., descriptive of a “few fragmentary bird-remains” recently obtained from the Tertiary deposits of the Siwaliks, and preserved in the Geological Museum at Calcutta. The subjects of most interest alluded to in this memoir are some bones referred to Dromœus, by Mr. Lydekker, and his remarks thereon, and upon some bones of kindred birds which form part of the extensive series of vertebrate remains collected in the same range of hills by the late Colonel Sir Proby T. Cautley, then Captain in the Bengal Artillery, and presented by him to the National Collection.

For the purposes of a memoir, about to be published by H.M. Geological Survey of England, on the Geology of parts of Norfolk, I have been for some time past engaged in a critical examination and revision of such lists of the so-called “Pre-Glacial Forest Bed” Vertebrata, as have appeared from time to time in various publications. And it is intended to publish the results of this work in detail, when figures of the more important specimens will be given, together with particulars of the reasons for the alterations and additions which it is deemed necessary to make. It seemed desirable, however, as some time must elapse before the entire work can be accomplished, to publish, as occasion serves, short notes of some of the changes about to be made; and it is hoped that these notes will not be without interest to the readers of this Magazine.

I have just read Mr. Hill's criticism on my views as to the cause of the Glacial Epoch, and have to thank him for the fair and courteous way in which he has treated the subject. I fear Mr. Hill has come to his conclusions somewhat too hastily. He appears to me to have totally misapprehended the real effect of fogs and a snow-covered surface on climate, and also the influence of eccentricity on the trade-winds. But I must defer for the present entering into any discussion on the matter. My object just now is simply to direct attention to an erroneous assumption which appears to lie at the base of nearly all the objections which have been urged against the theory that the Glacial Epoch resulted from an increase of eccentricity.

In the following notes we propose to collect descriptions of some of the igneous rocks on N. Wales founded on the collections made by the late Prof. Sedgwick many years ago. It is hoped that it may be of interest to readers of this Magazine, as many students turning their attention to rocks find a want of information in text-books concerning precise localities in Britain for the occurrence of many interesting types. Following Sedgwick's steps may help them partly to what they require, while the microscopical analyses appended will doubtless prove an aid to beginners, besides being a definite record, as far as it goes, of some types of Welsh rocks.

For many years past I have been familiar with the Trias of Staffordshire, but of late I have been noticing more carefully, during my occasional visits to that county, the pebbles in the Bunter, in the hope of being able to identify the parent rocks from which they have been derived. It has already been regarded as almost certain that many of them have a northern origin: and with, this idea in view I observed last summer the lithological character of the quartzites near Loch Maree. Although the results at which I have arrived are very incomplete, I think more good will be done by publishing them than by waiting, because, as it seems to me, they settle one or two points of importance, and because a question, like that of the origin of the pebbles in a deposit so widely spread as the Bunter, is one which can be better determined by a number of observers living in different localities than by any one person, especially if, like myself, he has but little time to spare for the investigation. If, however, I can show that one or two points may be regarded as fairly certain, it will very much facilitate the work of such observers. This work, the careful scrutiny of the contents of conglomerates, is one of more importance than may at first sight appear, because a rock fragment no less, and sometimes more, than a fossil records certain facts in the physical geography of the deposit in which it is found.

Observations on Spirorbis.—In the foregoing history I have endeavoured to give a brief and clear outline of the views held by those who have made it the subject of their investigations since the time of W. Martin.

As so much remains to be done before the Palæozoic Polyzoa can be properly classified—more particularly the Carboniferous species—it seems to me that the wisest course to adopt is to go carefully over the work of other authors, reviewing their labours generally, and giving, in as condensed a form as possible, the results of their varied efforts.

I am indebted to the kindness of Dr. Julius von Haast, F.R.S., Director of the Canterbury Museum, New Zealand, for the specimen which is the subject of this note. The little packet of fragments was labelled Moa Hunter, Kitchen Midden Sandhills, near Moa Cave, Point Sumner, New Zealand.

Since my former paper on the rocks of the Curlew and Fintona districts was published, I have had an opportunity of more carefully examining these districts. Both are eminently favourable for the theoretical geologist, as in them the rocks are much obscured by drift; however, for a careful and painstaking explorer, there are sufficient sections exposed, to show the geological age of the rocks. The accompanying diagram represents the rocks as they occur in the Curlew Mountains district.