When President Van Hise finished his address before the Geological Society of America last winter, which the Society has just issued, he leaned over benignly and glanced at Dr. Coleman, Professor Lawson, and myself, and said that while it was not customary to discuss the President's address he hoped in this case the custom would be waived, as he knew a number of members disagreed with him, and he felt they would have criticism of value to contribute. Whereupon ensued a most friendly but lively discussion, in which many took part. It has not been the custom of the Society to report such discussions, but I am sure that Van Hise will not object to see some of the points raised by the writer in print, as well as his Address.

The Cynodont reptilia from the Lower Karroo rocks of South Africa, characterized by relatively large incisors and relatively small, sharp-pointed, molar teeth, were grouped under the type genus Lycosaurus as Lycosauria. The removal of matrix from the palate of Ælurosaurus showed that in one member of the group at least the palate carries patches of teeth, each of which has the form of a small blunt flattened cone. From the fact that no Cynodont skull is available in which the mandible is free from the head, the nature of the palatal dentition is imperfectly known.

More than sixty years ago Mr. G. B. Sowerby, jun., described and figured a unique specimen of a remarkable fossil Cirripede from the Chalk of Kent which he named Loricula pulchella. It was obtained by Mr. N. T. Wetherell, F.G.S., of Highgate, and was subsequently acquired with that gentleman's collection by the British Museum (Natural History). Mr. Wetherell's Loricula was again described and figured by Charles Darwin in his “Monograph on the Fossil Lepadidæ or Pedunculated Cirripedes of Great Britain.”

1. The ancient core of the North-East African Continent consists of the Cataract and Sudan banded gneisses, which may represent a very ancient igneous magma. They are usually much veined by granitic dykes.

2. In certain places in the Arabian Desert, Cataracts, etc., these underlie highly metamorphosed schists (the mica-schists of Sikait, the calcareous schists of Um Garaiart and Haimar and of the Amara Cataracts, also the dolomites of the latter region) which are sharply separated from the banded gneisses and are possibly the oldest sedimentary representatives in Egypt.

3. The greater part of the mountainous regions of the Eastern Desert and Sinai are occupied by two types of rocks, a schistose constituent overlying or being surrounded by the acid member. (a) The first-named, the Dokhan volcanic rocks and schists, are partly volcanic in origin and partly sedimentary, the former being represented by lavas of various types, while the latter are clearly altered sedimentary strata (grits, conglomerates, etc.). No fossils have yet been found, but they have their nearest lithological analogues in the latest pre-Cambrian and Cambrian series. Here are included some of the most interesting rocks of Egypt, such as the Imperial Porphyry and the Breccia Verde Antico. (b) The igneous member intruded into these ancient sediments, etc., includes a great diversity of igneous rocks, varying from highly basic to acid types.

Contact-phenomena of complex nature occur at the junctions of (a) and (b).

4. Red granite and dyke rocks, whose parallelism and extent of distribution present one of the most conspicuous features of the Eastern Desert of Egypt, mark the final eruptive action before Carboniferous times.

5. Three periods of volcanic activity have been subsequently noted—

(a) In Western Sinai in late Carboniferous times.

(b) An undated series of eruptions interbedded with the base of the Nubian Sandstone or intrusive into it with marked contact alterations.

(c) The basic intrusions near Cairo and the Fayum, etc., which are intimately associated with the Oligocena Continental Period in Egypt.

The Inferior Oolite and contiguous deposits of the neighbourhood of Doulting have been described in detail in my paper on “The Inferior Oolite and Contiguous Deposits of the Bath-Doulting District”; but since that paper appeared, through the courtesy of the Urban District Council, I have had the loan of the John-Phyllis. Collection of Inferior-Oolite fossils that are housed in the Shepton-Mallet Museum.

In attempts to unravel some of the weightier problems of geology it has lately been assumed that certain discordances of stratification are due to the thrusting of old rocks over those of a later geological age. Without in any way suggesting that the geology has in any particular instance been misread, I should like to point out the difficulties in accepting the explanation looked at from a dynamical point of view when applied on a scale that seems to ignore mechanical probabilities. Some of the enormous overthrusts postulated are estimated at figures approaching 100 miles. Have the authors considered that this means the movement of a solid block of rock or rocks of unknown length and thickness 100 miles over the underlying complex of newer rocks? If such a movement has ever taken place, would it not require an incalculable force to thrust the upper block over the lower, even with a clean fractured bed to move upon? Assuming that the block to be moved is the same length as the overthrust, the fracture-plane would in area be 100 × 100 = 10,000 miles. I venture to think that no force applied in any of the mechanical ways known to us in Nature would move such a mass, be it ever so adjusted in thickness to the purpose, even if supplemented with a lubricant generously applied to the thrust-plane. These are the thoughts that naturally occur to me, but as my mind is quite open to receive new ideas I shall be glad to know in what way the reasoning can be met by other thinkers.