The study of the crystalline and metamorphic rocks seems hitherto to have been rather avoided by British geologists, who have more exclusively devoted their attention to the stratified and fossiliferous deposits, and left this field of research all but entirely to be cultivated by their continental brethren.

The extinct cartilaginous fishes represented in ‘mountain lime-stone’ and similary aged carboniferous formations by detached teeth, or dental masses adapted for crushing, have been referred to the Cestraciont family; and, so far as I know, have now no nearer living representative, in the class of fishes, than the Port Jackson shark (Cestracion Philippi.)

The occurrence of “Sarsen-stones,” or blocks of so-called Druid sandstone, has not, I believe, been generally noticed in this locality, and their position may be of interest to some of your readers, more especially as the extensive working both for Brick-earth and Chalk have obliterated many of the interesting sections for which the pits were celebrated. Grays is well known both for its fine chalk-pits and extensive brick-earth deposits, the latter containing numerous remians of fossil mammalia, associated with land and fresh water mollusca. The sarsen-stones (of which some may be still seen lying about the large chalk-pit), I have noticed during the progress of the workings as occurring on the upper surface of a bed of disturbed chalk, above the solid chalk, and covered by a blackish or carbonaceous clay containing freshwater shells.

Some time since, my colleague, Dr. Percy, purchased from Mr. Griffiths, Some of Folkestone, and sent to me, certain fossils from the Chalk-marl near that town, which appeared to possess unusnal characters. On examining them I found that they were large scutes and spines entering into the dermal armour of what, I did not doubt, was a large reptile allied to Soelidosaurus, Hylœosaurus, and Polacanthus. I therefore requested Mr. Griffiths to procure for me every fragment of the skeleton which he could procure from the somewhat inconvenient locality (between tide-marks) in which the remains had been found, and I eventually succeeded in obtaining three teeth, with a number of fragments of the vertabræ, part of the skull and limb-bones, besides a large additional quantity of scutes. I am still not without hope of recovering other parts of the skeleton; but as the remains in my hands are sufficient to enable me to form a tolerably clear notion of the animal's structure, a brief notice of its main features will probably interest the readers of the Geological Magazine.

Professor Huxley's communication, relative to the discovery of a new Reptile in the Lower Chalk of the south of England, which he has called Acanthopholis horridus, may be rendered more interesting by a detailed description of its stratigraphical position and its associated organic remains, a matter of some importance in this cases, as few, if any, higher reptilian remains have occurred in the Lower Chalk of either Europe or England; whereas in the Wealden group below the Cretaceous rocks, and still lower, in the Oolites and Lias, many genera occur. The discovery by the Rev. W. Fox of a remarkable and allied reptile in 1866, from the Wealden beds of the Isle of Wight, named Polacanthus by Professor Owen, increases still more the interest of this new genus, and is another reason why it is well to understand its geological horizon.

Any observations which can throw light on the systematic position of the Graptolitidœ are of great importance. That these anomalous fossils are Zoophytes, in the wide sense of the term, is almost universally conceded; the diffculty is in determining whether they are cœlenterate or molluscoid. Those who have described the members of the family have almost invariably considered them to be hydrozoa, and it must be allowed that in general aspect they very much resemble Plumularia and Sertularia. But when their structure is examined it will be found that they widely differ from any known hydrozoon, and especially in that the entire polypidom is composed of the different polype-cells, without any distinct common canal. Sometimes the polypes rise from a common substance which extends along the whole of the celluliferous portion of the organism, but there is no constriction or septum at the base of the cells, cutting off this common substance from the individual polypes. This is the structure of Graptolitus priodon, Bronn. In other species the walls of each cell seem to be continued to the solid axis, as is the case most probably in Graptolitus sagittarius, L. and certainly in some the species with a double series of cells, as Diplograpsus folium, His. D. pristis, His. and D. cometa, Gein. The mouths of the cells are frequently furnished with one or more long spines, as in some species of Bastrites, and in Diplograpsus pristis, His. In these characters the graptolites show a greater affinity with the polyzoa. Compare the genera Scruparia and Bicellaria. But there are some peculiarities which do not well agree with the living forms of either section zoophytes. Among these may be mentioned first the prolongation of the solid axis in both the unilateral and bilateral forms beyond the celluliferous portion in the newer part of the polypidom, and then their free polypidoms, for neither the spines which terminate the older portion of some species of Diplograpsus nor the slender base of Dendrograptus linearis, Car., could be radicles, and the species of the genus Graptolitus have no indications of a hydrorhiza from the older extremity.