The paper of Dr. A. Kunth, “Ueber Pteraspis,” Zeitschr. der Deutscheri Geol. Gesellsch., 1872, Hft. 1, came into my hands at a time when I had just been examining the specimen of which a restored figure is given in the Plate accompanying this paper. I took an early opportunity of replying to Dr. Kunth's adventurous assertions in the Academy, and the remarks then made have been reproduced in, this Journal (April, 1873). I need, therefore, here, in reference to that matter, only make one or two additional observations Dr. Kunth based his statements on a single specimen in a bad state of preservation. His figure shows how inadequate the specimen is to support his views. Out of the many hundreds—I may even say thousands—of specimens of Heterostraci which have passed through my hands, I could easily pick several exhibiting all varieties of juxtaposition of Pteraspis with Scaphaspis, and of specimens of a single species of either genus with other specimens of the same species. The packing of several shields one within another not unfrequently occurs, as happens very generally in the embedding of concave shells. The mere association of these shields, as in Gallicia and in Herefordshire, is not a phenomenon on which any one familiar with them—through examination of numbers of specimens from various localities—would venture to base any argument as to structural connexion.

Many curious cases of rock fissuring have attracted my attention while working out the geology of part of the English Lakedistrict. A notice of some few of them may perhaps draw forth remarks from those who have had longer and wider experience in the field of nature.

The subject of Captain Hutton's lecture, on the Formation of Mountains, delivered at Wellington, New Zealand, is one which has engaged a good deal of my attention, and was discussed by me in a paper read before the Cambridge Philosophical Society, and printed in their Transactions. In that paper I attributed the elevating force, which has raised mountain ranges, to the contraction of the heated interior of the earth, and subsequent wrinkling of the crust so as to accommodate itself to the diminished nucleus. This was an old hypothesis, but I believe the amount of horizontal pressure produced in that manner had not been estimated before. Mr. Mallet, the eminent seismologist, read a paper on the same subject before the Royal Society in May, 1872, in ignorance of what I had written, and came to the same conclusion as myself as to the amount of the horizontal pressure.

During several years I have had frequent opportunities, in my spare time, of collecting and studying the Crinoidea, particularly those of the Carboniferous formation; bat I have not had time, nor do I feel competent, to treat this subject fully in all its bearings. Perhaps, however, a few further notes on what I have observed in connexion with them, and in their relations with the recent as well as with those found in the several geological formations, may have an interest for some of your readers, or may be suggestive of further examination by some one better qualified, by physiological knowledge, for the inquiry.

The Upper Greensand of Cambridge occurs as a thin but very important bed, covering the eroded surface of the Gault, and blending upwards into the overlying Chalk-marl. It consists essentially of Chalk-marl, saturated with green grains of Glauconite, and crowded with a variety of fossils. The fossils in great part derive their origin from the Gault, out of which they have been concentrated by a natural process of levigation. At the time when the Gault sea was shallowing to its close, its submarine shores became eroded by a cold current flowing from the north, which bore away its lighter sedimentary clay, and left its imbedded fossils behind, to be subsequently rolled into the sublittoral deposit of the Upper Greensand. Thus it happens that in our neighbourhood the uppermost beds of the Gault are not to be found, and their only representative is this mere pebble-bed at the base of the Chalk. The rich fauna in our formation thus collected ready to the hand of the Palæontologist has been well worked out in its higher developments by Mr. Barret, Mr. Seeley, and various other observers. Of the Protista and Cœlenterata, however, some departments have been left all but untouched; and it is to the Sponges of the latter and the Foraminifera of the former that my paper refers. The Foraminifera occur abundantly, and in a rich variety, which seems to anticipate their more luxuriant appearance in the succeeding Chalk. The Vitrea perforata are represented by large forms of Bulimina, Textularia, and Orthocerina, which mimic truly arenaceous foraminifera by imbedding the siliceous and volcanic sand of the formation in their tests.