instruments were driven first inwards so as nearly to meet, and then opened suddenly outwards with various degrees of force. The stroke was, if I interpret the direction of the tracks rightly, a little backward as well as inward in each case, and the return stroke also backward.

The evidence, then, as far as I understand it, is, that one pair of organs placed near each other, and acting in a direction transverse to the progress of the animal, were the means by which the creature was propelled through the shallow water. Also that a posterior lobe or supplementary organ, shorter than the other, touched ground in the deeper imprints; but as it occurs only behind the deeper ones, which happen in this case to be on the left side, the inference is that there were a pair of such shorter organs immediately behind the longer pair.

Such an arrangement excludes, of course, the gigantic crustaceans described by Prof. Huxley and myself*, and now being so thoroughly examined by Mr. Henry Woodward. The Pterygoti are indeed plentifully found in the Kington Sandstones. Perhaps the largest of them all, at least the P. gigas, rivals the great Forfarshire species in size, and must certainly be 6 or 7 feet in length, as I at first supposed. But the struggles of such an animal in the shallows would leave, not a bilobed imprint, at times unequal-sided, but a number of impressions, arranged along a central line. Such are shown in Prof. Owen's illustration of the Protichnites of Canada, which that distinguished naturalist refers without much hesitation to large Limuloid or Eurypteroid Crustacea. In that view I thoroughly agree with him, and believe we have yet to discover the ancestor of all the Pterygoti in the Potsdam Sandstone.

That we may eliminate all the contemporary crustaceans from consideration, I may mention that I have myself described tracks of the Phyllopod Crustacea found in Lingula-flag and Silurian rocks, and made with double or triple forked caudal extremities (Quart. Journ. Geol. Soc. vol. x. p. 211, vol. xviii. p. 347). Such impressions have nothing in common with these. They were made in the opposite direction to that of these imprints, namely, fore and aft, in the line of the track itself.

But if we turn to the abnormal Ludlow fishes, Pteraspis (the earliest known of these) is common enough in the Kington Sandstones, as Mr. Banks's researches first proved to ust. These seem to give a clue to the impressions before us. If such fish, evi

dently fond of shallows, were endowed with stiff defences to their pectoral or ventral fins, they might produce with them somewhat such a pair of combined strokes as would lift the animal forward or backward. The slight obliquity of the stroke is not against the supposition; for the motion of a fish's fin is not quite in a direct line, but more like that of a screw propeller.

That Pteraspis had such stiff defences I do not know. But a not very distant ally among these abnormal cuirassed fishes (Pterichthys) Monograph of Pterygotus and Eurypteras, Mem. Geol. Survey, 1859. + Quart. Journ. Geol. Soc. vol, xii. p. 93.

had very decided bony crutches as a modification of its pectoral fins; and therefore I think we need not reject such a supposition too hastily in the case of Pteraspis. We have not yet been able to refer all the bony defences (Onchus, as they are called) which abound in the Ludlow bone-bed, the Downton Sandstone, and the fish-beds of the Old Red, to Placoid fish; and we may yet be led by these few tracks on sandstone to look out for such adjuncts to the fore limbs of Cephalaspidæ.

At least, all I can say is, that if Pteraspis had not such a bony crutch, I do not see how he could make such an impression on the sand; and if my impression is not a correct one, I cannot offer a better, nor suggest what aquatic or amphibious creature could possibly produce successive impressions of the form and direction I have shown to occur in these, unless it were Pteraspis, or the Acanthodian or Squaloid fishes before mentioned.

And now comes a very interesting point in proof that these imprints were made by fishes. If the water were not quite deep enough to float the animal (and that it was not, in the case of track A A*, is certain), then the stroke made by the leaning side must necessarily be shorter and somewhat deeper, and the fin itself behind the defence would touch the ground. In proof that these imprints (fig. 1) are the records of a struggle to attain the water, I need only refer to the specimens (which are placed in the Society's museum), where, on the back of slab 1, the weight of the instruments has been such as to indent the sand for more than half an inch, and to penetrate into a layer below, which is, of course, not seen in this specimen.

I owe the recognition of this circumstance to Prof. R. Owen, whose acumen in determining track-markings is almost an instinct; and to whom I showed the slab, telling him that I had come to the conclusion it was made by a fish (Pteraspis), and could be made by nothing else. His reply was very characteristic; for, turning up the back of the slab, which I had neglected to do, he at once pointed out the depth of the two impressions, which must have been made when the creature was struggling on the shore; and though he did not hastily adopt my conclusion, he at least convinced me that, if the track was made by a fish, it was a fish out of water.

4. On a NEW LINGULELLA from the RED LOWER CAMBRIAN ROCKS of ST. DAVIDS. By J. W. SALTER, Esq., A.L.S., F.G.S., and H.

HICKS, Esq. FOSSILS in the red Cambrian rocks are so rare, that no apology seems due for introducing a single small specimen, lately gathered, after great research, by one of the authors of this paper. The search has been systematically pursued since 1862, when the first fossil of the Menevian group was described by Mr. Salter from this neighbourhood; and the labour has chiefly fallen upon Mr. Hicks, who resides at St. Davids. He has literally not left a stone unturned to find the

true place of Oldhamia, and, if possible, of the mythical Palæopyge, in these old red rocks. He has been rewarded, during the search, by many additions to the Menevian fossils, found at successively lower and lower horizons, in the grey rocks which form the passage from the Lower to the Upper Cambrians. But, until quite lately, not a vestige had occurred to him in the actual red rocks themselves.

The fossil is but a small one, a line and a half long; but it is unquestionably a Lingulella, and apparently of the same species as one very common in the lowermost of the layers which have yielded Paradoxides, and the fossils of which will be described in our next memoir. With the Paradoxides Hicksii, Salter (the species formerly published in Siluria, 2nd edit., as P. Forchammeri?), several species of shells, Brachiopod and Pteropod, occur-and among them a Lingulella, of which figures and a description are appended, and which appears to be the same as that now found 200 feet lower in the red Cambrian slates.

LINGULELLA FERRUGINEA, Salter, spec. nov. Fig. 1.

Length fully 24 lines. Form ovate-oblong, the front rather obtuse, but not straight-edged; the sides nearly parallel; the obtusely pointed beak includes an angle of about 75°. Generally convex, especially down the median area; the sides bevelled obliquely; the surface concentrically and very finely striated; the inner surface rather coarsely sulcate concentrically, indicating close ridges or sharp waves of growth upon the outer surface (not visible in our specimens). The inner surface (and probably the outer) shows radiating lines (rather coarse ones) over the median area, but not on the sides.

The pedicle-groove is so wide and pyramidal as to open at an angle of 40°; and its edges are so strongly pronounced as to give the appearance of hinge-plates. A short median ridge divides this area, and extends but a very short distance. A specimen, apparently of the shorter valve, has also a median line, but fainter and longer. This is uncertain, the specimen being much crushed.

Loc. Lowest strata of the black flags in the Menevian group, Peny-pleidiau, St. Davids.

Fig. 1. Lingulella ferruginea, Salter. Natural size.
2. L. ferruginea, var. ovalis, Hicks. Natural size.
3. The same, magnified.

Var. a. OvALIS, Hicks. Figs. 2 & 3.

Shell ovate, 1 line long: front edge rounded, not obtuse.
Loc. Red Rocks of the Menevian group, near St. Davids.

Except the shape of the front edge of this small shell, which is rounded off, and not squared at all, this variety is not to be distinguished from the other.

We give this variety a distinct varietal name, as it is important to distinguish all marked forms. When there is a difference in geological position, as well as some peculiarity in the form, it is wiser to distinguish, at least as a variety, any important specimen. Until it shall have been clearly proved, by intermediate forms, to belong to the self-same species, there can be no reason for allowing a theoretical opinion of descent with modification to influence us, as naturalists, in determining the nomenclature of a fossil or recent shell. And the contrary proceeding would throw all our useful binomial or trinomial appellations into oblivion; while it would not advance by one iota the real study of the group to which the fossil belongs.

That Lingulella ferruginea, var. ovalis, may have been the progenitor of the more ordinary variety, which is found in rather newer beds, is probable. That both may be only steps in the series by which we at last reach, through several Lower Lingula-flag species, the characteristic Lingulella Davisii and L. lepis of the Ffestiniog and Tremadoc groups, is also possible, if not highly probable. But we have no proof of it. Still less have we any proof that Lingulella merges into Lingula, or this into Obolella, or the last into Discina, &c., or that any or all of them had some common ancestor of whose nature we know nothing.

I only intend by these remarks to show the importance of still adhering, in our nomenclature, to old and well-established rules. Whatever may be our theory as to the derivation of species, it behoves us, as descriptive naturalists, to keep our minds free from the delightful fetters of theory, while we strictly and truly describe the medals of creation as they are shown to us.

I think my friend Mr. Davidson, in whose acumen and talent I have profound confidence, has of late years set us a bad example in this particular. He merges Lingulella in Lingula (though one has a pedicle-groove, and the other has not), and Trematis in Discina (though one has a marginal foramen and a radiated surface, and the other a closed foramen, and a horny concentrically ribbed shell).

I may mention, while speaking of fossils from the Lower Cambrian rocks, which I regard as a portion of the great Menevian group, that Mr. Alfred Marston, of Ludlow, has within the last few years found other portions of the so-called Palæopyge, or some allied crustacean form. They are in the truly rich museum in Jermyn Street. He has also lately sent me word that my small Arenicolites are not the only tenants of the Longmynd. A large worm-tube, comparable to the Histioderma of the Wicklow rocks, has been found in the Longmynd by him.-J. W. S.

5. OBSERVATIONS on CERTAIN POINTS in the DENTITION of FOSSIL BEARS, which appear to afford good DIAGNOSTIC CHARACTERS, and on the RELATION of U. PRISCUS, Goldf., to U. FEROX. By GEORGE BUSK, Esq., F.R.S., F.G.S.

[The publication of this paper is unavoidably deferred.]

(Abstract.)

AFTER noticing the difficulties which attend the study of the bones of the skeleton generally in fossil Bears, and the somewhat confused and contradictory opinions as to the distinction of species which have arisen in consequence, Mr. Busk states that his object in the present communication is merely to call attention to some points in the dentition which seem to afford more certain and more readily ascertainable characters than can at present be drawn from the bones, and which, at any rate in the absence of other evidence, are a sufficiently sure guide in the distinction of species.

The characters derived from the teeth depend

1. On their dimensions, absolute and relative.

2. On their form.

It is not necessary, however, to consider all the teeth. The canines vary too much even within the limits of one species to be of much utility; and, with certain exceptions, the differences exhibited in the molars are not sufficiently marked to allow of their being employed.

The teeth upon which reliance is to be placed are the upper and lower fourth premolars, and the last molar in each jaw; and the distinctive characters of these teeth in U. spelaus, U. priscus, U. ferox, and U. arctos are pointed out by the author.

It is also endeavoured to be shown that in the size, proportions, and form of the teeth no essential differences can be perceived between U. priscus and U. ferox; and the opinion is expressed that, so far as cranial and dental characters are concerned, those two species are at present indistinguishable.

6. Notes on the GEOLOGY of the PROVINCE of CANTERBURY, N. Z., principally in reference to the deposits of the GLACIAL EPOCH at the western base of the SOUTHERN ALPS. By JULIUS HAAST, Ph.D., F.G.S., &c.

I. Introduction.

CONTENTS.

II. Geological Structure of the Southern Alps.

III. Moraine-accumulations of the Postpliocene or Glacial Epoch.

I. INTRODUCTION.

In a paper laid before the Society at its Meeting of the 7th December, 1866, I offered a résumé of my views on the causes by which the glaciation of the Southern Island of New Zealand had been produced in Postpliocene times, giving at the same time a short description of the deposits of that interesting epoch, by which the slopes and valleys