I Have recently obtained from the Borough Lee Ironstone several specimens of a Selachian spine, apparently new, and showing several features of a very interesting character.

The deficiency of our knowledge of the organization and configuration of the Palaeozoic Selachii is an unfortunate fact too well known to biologists to render it necessary for me to dilate upon here. Immense numbers of genera and species have been founded upon detached teeth and spines; but as yet very few specimens have occurred, which threw any light upon the general organization and configuration of the ancient possessors of these now scattered relics.

The carnivorous Dinosauria form a well-marked order, which the writer has called the Theropoda, in his classification of this group. Although much has been written about these reptiles since Buckland described Megalosaurus in 1824, but little has really been made out in regard to the structure of the skull, and many portions of the skeleton still remain to be determined.

In determining the actual position of strata from the appearances presented by their exposed edges in natural and artificial sections, certain mathematical problems are of constant occurrence. To a field-geologist who is not content with rough guesses founded on judgments by eye, the solution of these problems is a matter of importance, and methods have accordingly been given for some of those most frequently met with. These solutions take the form of (1.) trigonometrical formulæ, which can be applied only with the aid of trigonometrical and logarithmic tables; (2.) tables specially prepared from these formulæ for use in the field; (3.) graphical methods, requiring only a ruler, scale and protractor, which may be conveniently combined in one instrument. Of the first kind is the formula for deducing the true dip of strata from two apparent dips, given in Green's Geology (p. 341, 1st ed.), etc. Among special tables are those of Mr. Jukes for finding the apparent dip in any direction from the true dip, and for connecting the dip, thickness and depth of beds: these tables are given in the appendix to the Survey Memoir on the Geology of the South Staffordshire Coal-field, and reproduced in Jukes's “Manual of Geology.” Graphical methods have been used for finding the true dip from two apparent dips: a method partly graphical but requiring a table of cotangents is given in Phillips's “Treatise on Geology” (p. 298, 5th ed.), and also by the Rev. E. Hill (Geol. Mag. 1876, p. 334); a purely graphical method by Mr. W. H. Dalton (Geol. Mag. 1873, p. 332); and an approximate method by Mr. Penning (Geol. Mag. 1876, p. 236), reproduced in his “Field Geology.” As Prof. Green has pointed out (ib. p. 377), the last-named method is equivalent to taking the angle for its tangent, and so applicable only to small angles of dip. Mr. Dalton's solution (loc. cit. p. 334) of another question, to find the effect on strata already inclined of a second tilt in a new direction, is only an approximation, and cannot be applied if the dips are considerable. It is erroneously assumed that the inclination of the strata in a direction at right angles to that of the second tilt is unaltered by the tilting.

The labours of Mr. Jex in the Eskdale fish-beds have brought to light another beautiful new fish, now in the British Museum. This is a Ganoid of the genus Elonichthys, and though represented as yet only by a single specimen, this is fortunately a very perfect one.

By the kindness of Dr. Henry Woodward, Keeper of the Geological Department of the British Museum, I have been furnished with a list of shells which have the locality “Mead End” attached to them in the Edwards Collection in that Museum.

Perhaps very few Tertiary formations have received a greater amount of attention from geologists and collectors of fossils, during the last forty years, than the Red Crag of Suffolk and Walton-Naze; and it seems singular that so few traces of land life have resulted from so much research. Although in its southern portions it is strictly a marine deposit, yet its distance from shore could not have been very great at any point; but putting aside the few plants and mammalian remains, most of which in the coprolite portion of the Red Crag are derivative, there is little evidence of its proximity.

In plates lxii. lxvii. lxviii. of part 7 of the “Fauna Antiqua Sivalensis” (1847) a large number of remains of Merycopotamus (nearly all of which are in the collection of the British Museum) are figured under the name of M. dissimilis, although some of them are distinguished as var. major and others as var. minor; and it thus appears that at that date the authors of the work quoted referred all the remains to one species. It is stated, however, in Falconer's “Palæontological Memoirs,” vol. ii. p. 407, note 4, that in 1846 Falconer considered that there were two species, which he proposed to call M. dissimilis and M. nanus; and some of the smaller specimens figured in the “F. A. S.” under the former name, bear upon them the latter name in Falconer's handwriting. In some manuscript notes of Falconer's, written at a much later date, the name M. nanus is once again employed (although the tooth to which it was applied does not belong to Merycopotamus at all); and it would therefore seem that Falconer had by that time reverted to his original view.

Of the abounding Trilobites which mark the faunas of the Lower and Middle Palæozoic rocks few survive into the Upper Palæozoic. Three genera, if indeed they really deserve that name, have been described from the Carboniferous beds in England—Phillipsia, Griffithides and Brachymetopus. Only the first of these is yet known to occur in American Palæozoic strata. But on the other hand two species of Proetus have been announced from America—a genus not yet recognized in England. It is true that the distinctions are so slight that possibly these last might be as correctly referred to Phillipsia as to Proetus.

The history of opinion upon the subject of cleavage seems to be this. Sedgwick had come to the conclusion that cleavage was a condition, “impressed on certain rocks and in certain regions by the operation of some very extensive cause, after the stratified rocks had undergone great displacement,” and he suggested that the cause might be some kind of crystallization. But Dr. Sorby discovered that the intimate structure to which cleavage is due is not crystallization, but a mechanical rearrangement of the particles of the rock: and he produced it artificially by squeezing clay containing flaky particles. Dr. Tyndall did the same thing with different substances, without introducing flaky particles. In either case it was by pressure that the result was obtained. Seeing therefore that pressure could succeed in laboratory experiments, and that cleavage in the field was ordinarily nearly at right angles to the direction in which the action of pressure might have folded the strata, it was natural to conclude that both folds and cleavage had been concomitant effects of such a pressure. And this appears to be the theory now generally adopted; and is of course in opposition to both of Sedgwick's conclusions. For my part I believe that Sedgwick was right in thinking that cleavage was produced by some very extensive cause operating after the rocks had undergone great displacement; while I agree with Sorby and Tyndall in attributing it to a mechanical action, accompanied with pressure. Nevertheless I do not think that this pressure was the same exhibition of force, that originally folded and elevated the rocks, as explained in Part IV. Thus I am in accord with each of these authors in the domain in which his authority stands highest.

Having, some time since, been favoured by Professor Ralph Tate, A.L.S., F.G.S., of the University of Adelaide, South Australia, with two fragments of Tribolites from the Parara Limestone, Yorke's Peninsula, I venture to place the same on record, and to add a few notes on their probable affinities

Having nearly completed the manuscript of a catalogue of some of the Orders of Fossil Mammalia in the Collection of the British Museum, I have thought it advisable to give a brief preliminary notice of some rather interesting points in connection with the structure and distribution of a few forms of Carnivora and Rodentia; in which orders I have now gone through the entire collection of specimens. I also notice one specimen to which I have assigned a new specific name; and another which does not belong to the collection of the British Museum. Several of the more interesting specimens will be illustrated by woodcuts in the forth-coming catalogue.

We are indebted for the Woodcuts accompanying this note to the courtesy of Dr. John Mickleborough, whose paper on the Locomotory Appendages of Trilobites we published in our February Number, p. 80.

They serve admirably to confirm the observations of Mr. E. Billings (published in the Geological Magazine for 1871, Vol. VIII. PI. VIII. pp. 289–294) on the appendages of Asaphus platycephalus. In Fig. 1, a, a, mark the position of the anterior pair of appendages; b, b, the 10th pair; c, the articulation between the carpus and propodos; d, the articulation between the propodos and dactylus; e, the lines to the letter e mark the position of the lamelliform ? branchiae beneath the pygidium.

Having completed the description of the mammals and birds at present known from the Siwaliks of India and Burma (a list of the former being given in the September number of this Magazine, pp. 426–8), I have thought it well to publish a short account of the distribution in time and space of the Siwalik genera of these two classes, as a prelude to a more extended notice, which I hope to give in the “Palæontologia Indica” when I have completed the description of the whole vertebrate fauna of the Siwaliks.

Shell conical, moderately long, with perhaps a rudimentary umbilicus. The complete spire would consist of about 10 whorls, which increase under a regular angle. The surface of the apical whorls in this specimen is not well preserved, but the five anterior whorls are in good condition; they are smooth, somewhat tumid towards the centre, and separated by a suture of moderate depth. Wavy longitudinal lines, apparently lines of growth, are observed, but there is no trace of any other ornament. Base of body-whorl smooth and almost polished, except where there has been a decortication of the outer layer of shell. This decortication, besides affecting a considerable area near the outer lip, has formed a belt in the posterior region of the base, thus producing a sort of false carination. In this way we learn that both inner and outer layers of shell were of considerable thickness. (N.B.—The shell is now mainly in the condition of spathic iron, coated and coloured with brown oxide).

Recently, while reading Dr. Davidson's description of his Eichwaldia Capewelli, Brit. Sil. Brach. Sup. pp. 140–1, I was much interested with that paragraph in which he states, “It had been suggested to me that the appearance of the sculpture of the surface of E. Capewelli is precisely that of certain Polyzoa one is accustomed to meet with in Palæozoic rocks, a fact that had struck Mr. R. Etheridge, jun., as well as Prof. Nicholson; but to accept the ornamentation as that of an encrusting Polyzoan we must suppose that the shell had been entirely replaced by the parasite, as sometimes occurs with Hydractinia. Sections, however, show a perfectly homogeneous structure of the whole thickness of the shell.”

In Darwin's recently published work on vegetable mould, allusion is made to the fact that “In countries where the summer is long and dry, the mould in protected places must be largely increased by dust blown from other and more exposed places.” A few lines further on, however, he states that “In humid countries like Great Britain, as long as the land remains in its natural state clothed with vegetation, the mould in any one place can hardly be much increased by dust.” To this statement no exception can be taken, if we remember that it only applies to a period when the climate is humid, and to a country clothed with vegetation.

It is a trite observation that truths which lie at our feet may be overlooked by the wise, and discovered by mere accident, or the chance step of some casual passer-by.

The several species of Eryon, described by various authors, appear to be distinguishable as separate genera, which are as definable from one another as from the recent forms of Polycheles and Willemœsia; but the variability appears not to be greater than in those that are separated in time through geological æons, than in those that are contemporaneous in geographical space.

A few bones of birds are recorded by Mr. Gerard Krefft as having been found in association with the remains of the extinct mammalia, which abound in the breccias of the caves and fissures in the limestone rocks of the Wellington Valley, New South Wales. The bird bones belong to various genera and species, but only those of the Emu seem, as yet, to have been identified, and these were in the possession of the late Rev. W. Branthwaite Clarke. They do not appear to have been described, nor is the number of fragments in the collection stated. Unfortunately Mr. Clarke's valuable collection was deposited for exhibition in the “Palace Garden,” a temporary building erected for the Intercolonial Exhibition at Sydney in 1879–80, and was consumed in the disastrous fire which destroyed the building and its contents soon after its close; and, as regards Mr. Clarke's specimens, the destruction of the material evidence on which the early appearance of the Emu in Australia was founded. However, there is preserved in the palæontological collections in the British Museum, South Kensington, a portion of a shin bone, that I discovered some years ago in a collection of fragmentary remains from the Wellington caves, presented to the National Collection by the Trustees of the Australian Museum, Sydney. The specimen is the distal end of a right tibia, somewhat mutilated, but is interesting as being additional evidence, still existing, of the Emu having been contemporary with the great extinct Marsupials; as such, and on account of the rarity of its remains, I have thought it worthy of a short notice. Compared with the tibia of an adult Emu (Dromaius Novœ-Hollandiœ), it is indistinguishable from it, but has belonged to a larger individual, as shown by the annexed few measurements, in inches and tenths.