The Phyllocarida, from North Wales, referred to in the lastReport (for 1892, p. 299) as having been lent by Mr. G. J.Williams, F.G.S., of Ffestiniog, have been duly examined, and several described and figured, together with some other specimens, in the GEOLOGICAL MAGAZINE for May, 1893, pp. 198–203, Plate X., by T. R. Jones and H. Woodward. These comprise Peltocaris Salteriana, sp. nov. (Fig. 1), Dipterocaris Etheridgei, J. and W., 1884 (Fig. 3), Aptychopsis Williamsii, sp. nov. (Fig. 7), Ceratiocaris insperata, Salter, 1866 (Figs. 8 and 9); besides a fragment? (Fig. 6), an undetermined specimen (Cut, p. 203), a Conularia (Fig. 2), and two Mytiloid shells (Figs. 4 and 5).

In a paper read before the Geological Society of London, in 1889, I contended that the biotite of the gneisses and schists of Malvern had been produced out of hornblende through the intermediate form of chlorite. As this mineral change is of capital importance in explaining the origin of the Malvern schists, I made it one of the principal topics of the paper, and I trusted that the evidence I offered in support of it would be considered adequate. The further communication on the Malvern rocks, which I read on April 26th of the present year, assumed the adequacy of this proof. I found, however, that in certain quarters some scepticism on the point still existed, and it was suggested that I had overlooked some of the chemical difficulties which seemed to forbid the acceptance of my view. I therefore crave permission to reply to this objection in these pages ; and I desire, at the same time, to point out that since the reading of my paper in 1889, the production of biotite from chlorite has been affirmed by several writers of admitted authority.

There are some points of special interest with reference to the Insect remains from the Bembridge Limestone, near Cowes, which seem to be worth recording. My friend Mr. Scudder, who has done so much to promote the study and elucidate the history of fossil insects, and who is our highest authority upon the subject, remarks in one of his papers in the United States Bulletin, that in no case had he observed the interior of any insect in a fossil state, and that the internal structure could hardly be expected to be detected.

Mention is made of this slab by Mr. E. Etheridge, jun., in his Presidential Address to the Royal Physical Society of Edinburgh, p. 50. The specimen is in the Museum of Natural History, Cromwell Eoad, South Kensington.

The slab shows a piece of fossil wood 2¾ in. long by about 1½ in. broad, the exact nature of which is not determinable on account of its bad state of preservation, but this is fortunately not germane to the subject; it lies flat and compressed and is surrounded on three sides by masses of Mollusca, in places two and three deep, which have doubtless been attached to the wood by their byssi. The anterior ends and in many cases the inferior borders are turned towards the piece of wood and are in close contact with it, while others are again attached to the first row, as in masses of living mussels.

It has been supposed, though I do not know who was the first to suggest it, that the total amounts of silica existing in the Chalk with flints and the Chalk without flints respectively are very nearly equal: the idea being that if the quantity of silica disseminated through the flintless Chalk could be accurately estimated it would be found to be nearly or quite as great as the amount existing in the shape of flints in an equal thickness of flinty Chalk.

Proceeding on this assumption it seems also to have been inferred that silica was originally disseminated through the mass of the Upper Chalk, and that this silica has in some mysterious way been concentrated into nodules and layers of flint, leaving the surrounding Chalk in the condition of a nearly pure calcareous material.

It is now a recognized fact that many igneous intrusions, especially of basic rocks, grow more basic in composition from the centre to the margin. This type, of what Vogt terms “magmatic concentration,” has been discussed by several geologists, who agree in supposing that in such cases a magma, originally homogeneous, has become differentiated by the migration of the less soluble (more basic) ingredients to the cooler marginal region of the magma-reservoir.