KEMABKS ON CEPHALASPIDES. 137

CEPHALASPIDES OF FORFARSHIRE.

SIK,—The communication in your num­ ber for this month (March) from Mr. G. Roberts, in which he carefully conducts the enquiring geologist over some of the most interesting Silurian and Old Red Sandstone districts in England, and clearly points out the places where the remains of these curious primeval fishes, the Cephalaspides, are to be looked for, makes me think that a short notice of what Forfarshire has done towards better­ ing our acquaintance with at least one of these fishes, the Cephalaspis, may not be uninteresting; for, although, fortunately for geology, Scotland has now no mono­ poly of Old Red Sandstone fishes, yet so far as I am aware no really perfect speci­ men of that fish has been found out of this county. In forwarding this notice, I can assure the reader that I am actuated by no desire to have my name in any way connected with " a memoir of the earliest known fish," or "the history of the first appearance of vertebrated life," my sole motive being, by giving so far as I can, a popular description of what is known of the Cephalaspis, to fan the by no means flagging zeal of local collectors to com­ plete our knowledge of this queer fish, and its congeners. Although tolerably well - preserved specimens of the Cephalic shield which covered the head of the Cephalaspis, are by no means rare, yet it is very seldom Cephalaspis in Mr. Powrie's collection. indeed that the body is disinterred from our rocks ; and as I do not recollect of more than the head of this fish having been figured in "THE GEOLOGIST," I prefix a rough pen and ink sketch of a rather com­ plete specimen from my own collection, reduced to one half the natural size. The very characteristic strong bony shield which protects the head, and from which the creature takes its name (being made up of two Greek words signifying a head and a shield), had been covered exter- VOL. IV. S 138 THE GEOLOGIST.

nally by small hexagonal ganoid scales. Near the centre of this shield two rather closely placed holes formed the orbits for the eyes. In one of the heads in my possession the eye-balls are finely preserved completely petrified; between the eyes were two ridges having an intermediate hollow or sinus extending from the eyes backwards. One of my specimens shows that these ridges united towards the posterior edge of the shield, forming evidently a strong defence. None of the many heads I have examined show the slightest evidence that this creature was possessed of teeth, or a mouth of the ordinary form ; this organ, I believe, being similar to the sturgeon, which royal fish, I have little doubt, had this comparatively small creature as its representative in these old world waters. Some of the cusps or sharpened points of the shield are very much elongated and toothed on the interior of the margin. The body as compared with the head was but small, very slender, and protected by bony rings, extending in a slanting direction from the back downwards, these again being covered by exceedingly minute rhomboidal scales; in this respect resembling the larger number of the fishes found in the lower beds of the Forfarshire Old Red, as GUmatius, Acanthodes, Diplacanthus, &c. In only one specimen have I ever observed these on all scales; but a portion of one in my possession shows a very perfectly preserved cast of them: its heterocercal tail was much produced and furnished with a very large and powerful fin. None of the specimens I have as yet examined show the slightest vestige of either anal or ventral fins. The existence of a dorsal is by no means established; had it existed it must have occupied a position very far back. This creature was, however, further remarkable for having two very large membra­ nous pectorals, attached immediately under the cephalic buckler, seemingly of a leathery consistence, and covered by small sub-circular or hexagonal scales. The pectorals were first discovered by me, in the specimen from which the figure is copied. The remains of Cephalaspis, generally associated with plates or other portions of the Pterygotus Anglicus, have been found in alnost all the places where the grey flagstones, generally known in commerce as the Arbroath pavement, and which crop out in so many localities in Forfarshire, have been wrought. It has also been found in a bright red micaceous sandstone, overlying and considerably above these flagstones, while in no case has the Pterygotus Anglicus been, up to this time, found in the sandstones overlying ^h& shales and flagstones of the Arbroath pavement. Although the above-mentioned flagstones are quarried in so very many places in Forfarshire, anything ap­ proaching to a complete specimen of this fish very rarely turns up indeed. I only know of some eight or ten specimens showing the body, having been as yet disinterred from the rocks in which they have so long been intombed. Perhaps the finest of these was several years ago got by the late Mr. Lindsay Carnegie from his quarries at Leysmill, and by him presented to the Arbroath Museum. The well- known specimen presented by Sir Charles Lycll to the British Museum was found in a quarry near the village of Glanmis. There REMARKS ON CEPHALASPIDES. 139

are three good specimens in the Montrose Museum, one of which was discovered in a quarry near Brechin; another is from the neighbourhood of Friockheim. I have also been able to secure three specimens in tolerable preservation. Two of these were found in a quarry at Legguston, near Friockheim. The only other specimen I know of, a very small one picked up by Mr. Walter McNicoll, in a .singularly rich deposit discovered by him in the Sidlaw range, is now in the cabinet of Lord Kinnaird. As already stated the buckler- shaped heads are occasionally met with wherever the flagstones are wrought, in some places rather plentifully, as in a. quarry on the Tur hill range, about a mile east from the Mansion House of Pitscandly, also in a Red Sandstone quarry near Brechin; yet even there these are only to be had by getting the workmen to preserve them as they turn up. Indeed I may saj' that the only locality which has as yet yielded these organisms to individual research is mentioned as dis­ covered in the Sidlaws by Mr. Walter MaNicholl, one of the most energetic and consequently successful of our local explorers. On the same slab on which Mr. McNicholl found the small entire Cephalaspis noticed above, may be seen the heads of some four or five others, some of these heads showing the very lengthened and toothed cusps above described. Whether these lengthened and toothed cusps may mark a different species from that generally found (Cephalaspis Lyellii) it is not my province to decide : my own impression however is that this rather points to difference in age or sex, most probably the latter. Should this be the case it is worthy of remark that only one species of Cephalaspis has yet been found in Forfarshire (in Scotland I ought lather to say), where the remains of these curious creatures have been found in comparative abundance and good preservation, while in the contemporaneous rocks of England, where, so far as I am aware, they are both rarer and much more fragmentaiy, there would seem to have been not only a considerable number of different species detected, but also the so nearly allied genus Auchenaspis. Could it be possible that the above causes, age or sex, should have occasioned this seeming variety of species—fracture and displacement of the parts when first laid down might also occasion very considerable apparent divergence. Beyond Forfarshire I only know of one locality that has been at all fruitful in these organisms, the well-known den of Balruddery, and this is just on the confines of the counties of Perth and Forfar. One or two heads have also been found in Canterland Den, in Kincardineshire, by the Rev. Hugh Mitchell, of Craig, A quarry in Sheriffmnir, not far from the Dunblane station of the Scottish Midland Railway, has yielded one imperfect head; and two have been got at Langfine, near Muirkirk, in Ayrshire. In no case has an entire fish been found in any of these localities. In this short notice of the Forfarshire Cephalaspis I have purposely endeavoured, as far as I could, to avoid all scientific names and phrases, so that my description might be as intelligible as possible to all your readers. I ought also to remark that although the proportions and 1

i

140 THE GEOLOGIST. position, &c, of the fish figured are as nearly as may be those of the ) specimen from which it is copied, other specimens show a considerably J stouter body. The scales are of course restored, only small patches of these being preserved on any of the specimens. The dotted lines meant to show the probable size of the caudal and dorsal fins, unless, : indeed, that figured as a dorsal had really formed only part of the i large tail-fin.—I am, your obedient servant, JAS. POWKIE, F.G.S., Reswallie, Forfar.

REMARKS ON MR. ROBERTS' PAPER ON CEPHALASPIS. • \

SIR,—I venture to send you a few comments on Mr. George Roberts's paper on Cephalaspis in your last number. \ How your correspondent, Mr. G. E. Roberts, can talk (page 103) ] of the Lower Ludlow at Leintwardine being " clearly marked out as j a littoral deposit" by its " starfishes," after his paper in the " GEOLO- j GIST" the other day announcing the discovery of starfish at one \ thousand two hundred and sixty fathoms depth, surprises me much. 'j Equally does it surprise me (especially since his connexion with \ the Geological Society) to find him talking of the " Tilestone series i passing into the underlying Silurian," when Sir R. Murchison, hi his last edition of Siluria, has laid down (though, I confess, with a < little confusion) that the beds between the Old Red and the Silurian j are to be called Passage beds, and are quite different from his original j Tilestones, which are clearly Upper Ludlow, being Downton Sand- j stone. As long as this inattention to proper nomenclature is per­ petuated, no one can understand what is written on the subject. The chief cause of error seems to lie in the end of the tenth chapter of Siluria, which appears to have been written before the present knowledge on the subject was obtained, and not corrected before sending it to press. The author there certainly speaks of the j Tilestones and Passage beds of Kington in connexion with Mr. ] Banks ; but those beds at Bradnor Hill are unquestionably Downton • Sandstone. They were formerly by some called " Transition beds" i (as marking the change to sandy from shaley beds), and were then \ considered to be equivalent to the Tilestones of Murchison, and which 1 Tilestones were afterwards considered by some to be the same as the \ Passage beds, which, in fact, lie some distance above them. There ] is no excuse for the mistake on the part of my friend Roberts, who 1 knows both series of beds well, and I am sure can see no similarity i between them. In fact (at page 106), he calls the Kington beds Downton, but oddly enough distinguishes between the Downton beds and the Upper Ludlow, of which they are the top. In the same ; page (at top) he speaks of Cephalaspids being " abundant in the '' neutral ground between the Downton and the Tilestones," which