Description.—Shell trigonal, thick; umbones large, angulated and terminal, ending in acute points, which curve downwards, forwards, and a little outwards; the sides of the shell, triangular in form, slightly excavated and highly inclined to the areas, are bounded by prominent carinæ, an acute carina separating the side from the slightly concave triangular area in front, and a more rounded carina separating it from the slightly convex triangular area behind. The valves are marked with strongly defined and somewhat sinuous subimbricating lines of growth at wide and fairly regular intervals, between which may be discerned numerous fine lines of growth. Lunule small and deep. Cardinal tooth elongated, oblique and prominent in the right valve, small and triangular in the left.

In a paper published in the Quarterly Journal of the Geological Society for 1884, I gave some account of the Tynemouth Dyke. In that paper, however, I omitted to describe one feature, connected with the microscopic structure of the dyke, because at the time of writing I did not understand it. A short time ago I had occasion to re-examine my preparations, when my attention was again directed to the feature in question; and this time an explanation suggested itself which appears to be in every respect satisfactory. The main object of this communication is to supplement my already published description by giving an account of the feature to which I have referred, and which may be briefly described as the occurrence of spherical patches of interstitial matter. (See Pl. XIV. Fig. 1.)

Vertebrate remains from the “Forest Bed” continue to be brought to light by the rapid denudation of the East Anglian coast, and I have again to acknowledge my indebtedness to Mr. A. Savin, of Cromer, whose assiduous collecting has preserved so many of these fossils, and made them available for scientific study. One of the specimens which he has now sent me is a species of Cervus, apparently new to science, while the others, although referable to living forms, are now for the first time definitely recorded from the “Forest Bed,” and if my determinations prove to be correct, the following names may be added to the list of Mammalia from this deposit:—

Cervus rectus, new species.

Bison bonasus, Linn., var. priscus, Bojanus (to replace Bos primigenius).

The subaërial deposits now accumulating in the arid portion of the United States may be divided into four classes: 1, Eolian Sands; 2, Talus Slopes; 3, Alluvial Cones; and 4, Calcareous Clays to which no specific name has been applied, but which, for reasons stated below, will be called “adobe” in this paper.

In a recent publication (“Anthozoen des rheinischen Mittel-devon,” 1889) Professor Schlüter has put forward the conclusion that the genus Syringolites, Hinde, is identical with the much older genus Roemeria, Edwards & Haime, the former name thus becoming a mere synonym. From this conclusion I feel obliged to dissent, and I propose to show in the following brief communication that Roemeria and Syringolites are distinguished by important morphological characters, and that the latter is fully entitled to generic rank.

The creature which forms the subject of the present communication is the same as that which was described as Asterolepis by Hugh Miller in his “Footprints of the Creator,” and consequently its remains are at present better known to British geologists and palæontologists under that name. Why, then, alter a name which we have used so long? is a question likely to be asked by those who have not critically studied the complicated mesh in which the synonymy of the name “Asterolepis” is entangled.

There always appears an objection to the agencies by which mountains and hills are formed being designated by such terms as “mountain architecture,” “ mountain building,” etc., leading to the inference that to the deposition of the materials which enter into their composition these elevated regions owe their form and structure. There certainly are mountains which have been built, and some such are at the present time in process of building; but these instances refer only to elevated masses of volcanic origin: they have been constructed as the railway engineer builds his embankments, or, with greater preciseness, as the miner forms the bank at the pit's mouth, by tipping over the rubbish brought from below. To hills and mountains forming volcanic cones the term mountain building is quite correct; the volcano in eruption pouring over its lava, and belching forth scoriæ and ashes, which fall and accumulate around its vent.

From the Old Red Sandstone of Caithness, four species of Dipterus were originally named by Sedgwick and Murchison, those being as follows:—

1. Dipterus brachypygopterus, anal fin short.

2. D. macropygopterus, anal fin long.

3. D. Valenciennesii, small in size, narrow in shape.

4. D. macrolepidotus, not characterized although figured.

It is evident from the figures of “D. macrolepidotus” that it does not belong to the same genus, even to the same family, as the other forms. Those have circular scales, whereas in “macrolepidotus,” the scales are rhombic, and the head bones are clearly seen to be very different from those of Dipterus.

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.

In 1884 I spent about a fortnight investigating the geological structure of these islands, and intended to have to a certain extent completed my studies at that time. Cholera was then raging at Campobasso on the mainland, and the islanders, not comprehending the curious habits of a travelling geologist, supposed I had been sent by the Government to spread the “Cholera Powder,” and requested me to leave the islands by the next steamer. This I naturally for safety's sake did, and opportunities for returning to the locality not having again presented themselves to me, and lest I should forget some of the interesting observations I then made, I think it desirable without further delay to record what I then saw. This is all the more important since my own observations differ considerably from those of the few other observers of the geology of these islands, or include facts which they do not mention in their writings.

Histionotus Angularis, was first described and figured by the late Sir Philip de M. Grey Egerton, Bart., F.R.S., in Decade viii. of the Memoirs of the Geological Survey, 1853. The uninterrupted dorsal fin, extending from near the occiput to the tail, suggested the generic name of Histionotus, and in this feature it reresembles Ophiopsis. It has the characters also of other genera, for instance, Pholidophorus in its scales, Semionotus in the shape of its body, and Lepidotus in the shape of its head. Sir Philip Egerton, misled by the imperfect preservation of the posterior end of his specimen, thought the caudal-fin to be also similar to that of Lepidotus.

In this specimen one valve (the left) and a part of the dorsal region of the other, remain visible; the rest of the right valve being bent down, broken, and imbedded in the matrix. This is a finely micaceous, non-calcareous, grey mudstone, weathering ferruginous towards one edge, which probably abutted on a crack open to water and atmosphere.

The fossil, in the grey portion is darker than the matrix, and fairly represents the test of half of the carapace, with only a very thin lamina wanting, a broken edge of which is traceable (with a lens) near the ventral margin. This left valve measures 9·2 by 7·4 mm. It is subcircular, more boldly curved on the ventral than on the posterior margin, whilst the front margin is somewhat truncate, having a nearly straight edge from above downwards before it bends round into the ventral curve.

I Will now put forward some details, for it seems necessary that some proofs of what has been maintained in general should be given, and I shall therefore quote some examples of the intimate connexion between earth-structure and terrestrial magnetism. No diagrams could indicate the relations better than Locke's Magnetic Sections across the Hudson, which were taken at three different points of the Palisades, Snake Hill, Fort Lee and Patterson (see Plate XV.). The dip and intensity were in each case determined at a number of points along a line perpendicular to the range of cliffs, and the curves rise very suddenly to maxima just above the edges of the cliffs, which are composed of columnar diorite. This diorite is widely distributed and lies between masses of Triassic sandstone; the dip is slight and towards the west.

A Comparison of adobe with the loess of China forms the concluding part of this paper; but as no analyses of the Chinese deposit are known to me, a few analyses of the loess of the Mississippi Valley are inserted, not with the assumption, however, that the deposits bearing the same name in these two regions are identical. A comparison of this table with the one showing the composition of adobe is instructive, as it indicates that these two yellow earths have a very similar composition. There are other respects in which they bear a close resemblance to each other; but as my acquaintance with the loess of the Mississippi Valley is limited, this comparison will not be carried further.

In the year 1841 Sir R. Owen described and figured a slab of rock from the Lower Lias of Barrow-on-Soar which showed the impressions of the bones and integuments of a pelvic paddle of an Ichthyosaurus, probably referable to the typical I. communis. In this specimen it appears that the integuments were produced to a greater extent on the posterior than on the anterior side of the bony framework; and that while the anterior margin of the soft parts showed evidence of squamation, the larger posterior flap was marked by oblique striæ extending from the bones to the periphery which appeared to have been caused by parallel bundles of muscular fibres. The distal extremity of the soft fin terminated in a sharp point far below the distal bones.

The largest mammals of the American Miocene were the huge Brontotheridæ, which lived in great numbers on the eastern flanks of the Rocky Mountains, and were entombed in the fresh-water lakes of that region. They were larger than the Dinocerata of the Eocene, and nearly equalled in size the existing Elephant. They constitute a distinct family of Perissodactyles, and were more nearly allied to the Rhinoceros than to any other living forms.

“What was the condition of our present mountain tract during the great Carboniferous period? Was it wholly submerged after the elevation and denudation to which we have already seen it subject, or was there always a nucleus of dry land—an embryo of Cumbria—around which the Carboniferous deposits were laid down? I do not think this is a question that can ever be decidedly answered.”

It is a question which has frequently been asked, and the answer given are various. In the present communication I intend to loo at it from a somewhat different point of view from that in which has usually been approached, though the view here adopted in man respects resembles that taken by the late Mr. Hopkins.

When the new railway from Nottingham to Market Harborough was made, several instructive sections in the Upper and Middle Lias series were opened out between the latter place and Tilton. Most of these are now covered up and grass-grown, but one of the best is still partially laid bare in the deep cutting at Tilton Station. This Tilton section has become one of considerable interest to the geologists of the Midland district, from the complete and characteristic exposure which it gives of the Marlstone Rock of Leicestershire in its fully developed and unweathered form, and also on account of the rich fauna which that rock, and in particular its top or ‘Transition Bed,’ has here yielded.

Until quite lately no fossils had been found in the Lower Cambrian of Bethesda. Indeed we had almost given up the hope of obtaining any evidence of the life of the period represented by them, because of the great alteration in the character of the rock resulting from the severe mechanical action to which it had been subjected. The announcement that Mr. Robert Lloyd had discovered fossils in the uppermost slate beds of the Penrhyn Quarries was therefore received with great interest, which was increased when it was found that some of these were in a sufficiently perfect state for determination, and that they were referred by Dr. Woodward to a new species of a well-known Lower Cambrian genus of Trilobite.

In the autumn of 1887, during a stay in North Cornwall, I paid a hasty visit to Tintagel, and took away a few specimens of rocks, without, however, having time or opportunity to examine more than very superficially into their field-relationships.