soil around.* One of the tanks contains nearly 200 crocodiles. There is a spring at no great distance which affords large deposits of sea salt.

The next volcanic group to be met with in this direction is that of Hinglay, a series of mud volcanoes very similar in point of form to those of Cheduba, along the sea-board of Lus, and now in great activity. Here there is no appearance whatever of there ever having been any eruption of lava. The first of these are called the Koops of Chimdra'; they are believed to be of Divine origin, and to be possessed of miraculous virtues.

The extent of this volcanic field has never been precisely determined; it extends some fifty or sixty miles inward, and at least three times as much along-shore.

The band, if band it be, now trends away southerly from lat. 22 to lat. 12°; and next group we meet in with is that at the mouth and lower part of the Red Sea, commencing with Cape Aden,† and concluding with Gibbel Teir, extending across from the former of these to the Salt Lake Assal, inland from Tadjoura-so inland for 100 miles.

Aden is spoken of by Arab writers as having been in a state of activity within the historic period; and though there scarcely seems evidence sufficient of this to be relied on, and a considerable presumption to the contrary, it has all the appearance of great recency.

(To be concluded in our next Number.)

*The hot spring takes its name from Peer Muggun, a Mohammedan saiut whose shrine is close by. The coincidence of the sound with the designation given to the long-snouted crocodile (muggun) had led to the iuference that it was Peer Muggun, the Crocodile saint. The crocodiles in the tank are of the kind called Gavial-they are precisely similar to those of the Nile and Ganges -not at all like the muggun,

† See Dr Bird's Notes to Captain Foster's Account of Cape Aden, Rombay Geographical Transactions. Referred to in Report of the Society for 1850,

vol. ix.

.

353

On Reptilian Remains found in the Old Red Sandstone of

Morayshire.

1. Notice of the Discovery of Reptilian Foot-tracks and Remains in the Old Red Sandstone of Morayshire. By Captain LAMBERT BRICKENDEN, F.G.S.

On the coast of Morayshire, between the villages of Covesea and Burghead, strata of crystalline sandstone occur in great thickness, and are regarded as belonging to the upper division of the Old Red or Devonian formation of Scotland. The only fossil discovered in this rock was the imprint of a mass of scales or scutes of a remarkable ganoid fish, named Stagonolepis, by M. Agassiz, until 1850, when the author observed on a block of sandstone, in a quarry at Cummingstone, a distinet series of quadrupedal footprints, traced in an uninterrupted succession across the slab. The imprints are thirtyfour in number, and the track of the right feet alternates with that of the left. These impressions have a rounded form, and are identical with those which are generally regarded as chelonian footprints by palæontologists. In October 1851, from a quarry of sandstone at Spynie Hill, Mr Patrick Duff, of Elgin, obtained a beautiful imprint of the skeleton of a four-footed reptile, about five or six inches in length, and which that gentleman allowed the author to transmit to Dr Mantell to describe, as an appendix to the present communication. The author states that, on finding the chelonian foot-tracks in rocks of an age in which no traces of the class Reptilia had previously been discovered, a strict investigation took place as to whether the sandstone strata, from which the slab was taken, are unquestionably referable to the Devonian formation, to which they had always been supposed, by Mr Hugh Miller and other competent observers, to belong. The discovery of the reptile at Spynie dispelled all doubt on this point; for the beds of Cummingstone and Spynie are identical, and, at the latter place, are capped by the cherty limestone peculiar to the upper division of the old red of the district. The Stagonolepis, found in the same rocks, is emphatically an old red sandstone family of fishes, and confirms the above inferences. The author concludes with the remark that, by the discovery of the chelonian footsteps and the reptile of Spynie, we have thus for the first time obtained unquestionable evidence that two orders of the class Reptilia existed during the Devonian epoch.

2. On the Telerpeton Elginense, a Fossil Reptile discovered in the Old Red Sandstone of Moray. By Mr PATRICK DUFF; and on supposed Fossil Ova of Batrachians in the lower Devonian Shales of Forfarshire. By Dr MANTELL, LL.D., F.R.S.. &c. The reptile from Spynie, referred to by Captain Brickenden in the foregoing paper, consists of the impression of the skeleton in a VOL. LII. NO. CIV.-APRIL 1852.

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354 Reptilian Remains in Old Red Sandstone of Morayshire.

block of sandstone, which is broken into three pieces. The cranium is but obscurely seen. Of the rest of the skeleton scarcely an atom of the osseous substance remains. The impression of the spinal column from the occiput to the pelvis, consisting of twenty-four vertebræ, each supporting a pair of slender ribs, of the left humerus, radius, and ulna, of the femoral and leg bones, of the pelvis, and of a considerable portion of the caudal series of vertebræ, serve to convey a general idea of the form and structure of the original, The authorTM gave a description of its anatomical characters, so far as they can be ascertained from the imperfect state of the specimen, and the result of a comparison with recent forms. He specifies certain osteological characters which are Lacertian, and others that are Batrachian; and he concludes that the original was a peculiar type, which, in the present state of our knowledge, it would be rash to pronounce to belong to either order; and he distinguishes it by a name simply ex-, pressive of its high antiquity-Telerpeton (rnλ igrov), with the specific term Elginense, to denote the locality in which it was dis-. covered. The original was an air-breathing, oviparous quadruped, probably resembling in appearance an aquatic salamander, but with longer limbs and a wider dorsal region than our Tritons, and capable of rapid progression on land and in the water. In connection with the above discoveries, the author states that the Devonian shales, of Forfarshire abound with clusters of small, round, carbonaceous bodies, which are commonly associated with aquatic plants. These fossils have been figured and described as being probably ova of gasteropodous molluscs, although neither shells nor casts of shells of any kind have been found in the strata. The discovery of reptiles in the upper member of the Old Red of Scotland led Dr Mantell to recur to an idea he formerly entertained, that the Forfarshire fossils were the spawn of Batrachians of the family Ranidae; and upon comparing them with a mass of carbonized recent frogs' eggs, the resemblance was found to be so complete as to induce him to conclude that the, fossil eggs are referable to reptiles and not to molluscs. In conclusion, the author dwells on the importance of the researches of Captain Brickenden and Mr Duff in a paleontological point of view; they establish the existence during the Devonian or Old Red epochy of several orders of a higher class of vertebrate animals than had previously been discovered; while the occurrence of Batrachian ova with aquatic plants, associated with remains of ganoid fishes, which, for aught that is known to the contrary, may have been inhabitants of fresh water, like the existing Lepidostei, together with the entire absence of marine organisms, suggests the probability that the Devonian strata thus characterised, may be of fluviatile origin.

for

As we have inserted in this number of the Edinburgh New Philosophical Journal a short account of Professor Sedgwick's. view of the Older Paleozoic Rocks of Great Britain, but chiefly those of the Cambrian System, we think it proper to give a place to the following letter, addressed by Sir R. Murchison to the Literary Gazette of the present date, on the Silurian System:

As the abstract of a memoir by Professor Sedgwick on the Palæozoic rocks, which appeared in your journal of the 6th, might lead some of your readers to suppose that the Silurian system is a baseless fabric which requires reconstruction, I beg permission to state the substance of the reply which I made viva voce at the rooms of the Geological Society, to the points advanced by my old friend, who has become an antagonist-the only one, however, I am acquainted with-to views which are. I trust, firmly established.

Divested of numerous local names, the proposition now brought forward (seventeen years after the promulgation of the Silurian nomenclature)* is, that a very large portion of the lower Silurian rocks described by me as the Llandeilo' formation, be transferred to the so-called Cambrian rocks.' On my part, I contend that geologists must adhere to my nomenclature, founded on data which have proved to be true-a nomenclature that has been generally adopted at home and abroad.

The few arguments required to sustain this position will be intelligible to every one. Let those who wish to comprehend what the Silurian system is considered to be by leading geologists, repair to the great and instructive geological museum in Jermyn Street. There they will see that all the inferior slates and limestones of North Wales which contain fossils are named Lower Silurian. They will also see that in the coloured maps and sections illustrative of North Wales, Lower Silurian rocks are represented to extend nearly all over that region; the only strata to which the term Cambrian is applied, being certain masses of unfossiliferous greywacke, which, like my Longmynd in Shropshire, rise from beneath the lowest fossil-bearing rocks. Why, then, did Sir Henry De la Beche, and his followers in the field, Ramsay, Aveline, Selwyn, and others, adopt this classification? and why has it been confirmed by Edward Forbes, Phillips, Salter, and the paleontologists of the Survey? Simply, that after a long and careful scrutiny these observers have

*See Philosophical Magazine, 1835, with table, &c. The large work really followed in 1838 (date of Preface), though 1839 is on the title page.

́satisfied themselves that the region called Cambria, at a time, it will be recollected, when none of its fossils were described, is made up of the same strata, and contains the same organic remains, as the lower Silurian rocks, whose contents were so long ago described by myself. Inquiries and researches in various parts of Europe, in which I have taken part, and in America and other countries, have been followed by similar results; and as the lower Silurian types of life have everywhere proved to be the oldest, the term Cambrian has never yet been applied to strata characterised by any group of animals peculiar to them.

The adoption of the proposal of Professor Sedgwick would, in truth, destroy the Silurian system of rocks. For whilst he leaves me the Caradoc sandstone, he would cut away from it the next underlying formation, or my own Llandeilo flags; though it is known to every one who has worked in these primeval rocks, that many of the same species of shells and trilobites characterise both the Garudoc and Llundeilo formations. How, then, is the geologist to draw any line of separation through the middle of a group, the members of which are thus naturally united? How call one part of it Silurian, and another Cambrian? How, indeed, break up a natural system of life in which a great number of fossils are found to be common to its upper and lower divisions?

That the Silurian base-line, on which Professor Sedgwick lays so much stress, was inaccurately defined in many parts when my labours in Siluria terminated, is very true; but it was essentially correct in Shropshire, and all that might lie beneath it was left to himself to determine. The chief phenomena I described in Siluria, after seven years of labour, have stood the test of time; and a companion whose friendship I shall never cease to value, must not lay to my door the loss of a Cambrian kingdom, in the occupation of which I had no share. Its invaders have been the geological surveyors, who literally could not do otherwise than interpret a region (the fossil contents of which had never been delineated) except by comparing it with tracts long well known, through my detailed descriptions of their rocks and fossils. These surveyors have shewn, that the very strata which in Shropshire and Montgomeryshire I described as lower Silurian, to the west of my Cambrian" Longmynd, roll over in great undulations to Snowdon itself. Hence it is now useless to refer back to the inaccurate portion of a line of boundary on my old map, which is little more than a demarcation between my own hunting-grounds and those of my friend. Cambria was, indeed, his own country, in which, amid grand contortions of the rocks, he had ably mastered many physical difficulties besides those of slaty cleavage and I respected this territory, in the full persuasion that its strata would prove to be of higher antiquity than my own, and, if so, that their contents would be distinct. The appeal to nature by our associates has decided otherwise.