742 Meeting of the British Association. [Oct., 



comparing early records with the present configuration of the coast of 

 France and of the Channel Islands, the author concludes that most 

 extensive changes have taken place during the historical period ; 

 subsidences, varying up to as much as 100 feet in some cases, having 

 occurred over considerable areas, as shown by a large coloured map 

 illustrating the subject. In a very analogous paper, by Mr. Pengelly, 

 " On the Isolation of St. Michael's Mount, Cornwall," it was argued 

 that subsequent to the occupation of the country by the ancient 

 Britons, who called this " the hoar rock in the wood," but yet anterior 

 to the period of the Romans (Diodorus Siculus, speaking of it as an 

 island), the rock had been so separated from the main land as to be 

 an island at high water. The author contended that separation had 

 been effected, not by the encroachment of the sea, but by a general 

 subsidence of the land. 



Amongst the papers related to districts of which the geological 

 structure is very imperfectly known, special reference may be made 

 to that by the Rev. W. Holland on the Geology of the Sinaitic 

 Peninsula. A most instructive collection of fossils was exhibited, 

 including cretaceous and older forms, amongst which was a well- 

 marked stigmaria. Some comparatively very recent deposits yield 

 distorted varieties of cardium, and indicate that the Red Sea was 

 more extensive, and that its waters were far less salt than at present, 

 and similar to those of the Baltic. 



Amongst the most striking palaeontological discoveries brought 

 before the Section was that of a fossil spider, from the coal measures 

 of Upper Silesia, described by Professor Romer of Breslau. A new 

 large saurian from the Wealden of Brook, Isle of Wight, was de- 

 scribed by the Rev. W. Fox, for which tbe name Polacanthus has 

 been proposed by Professor Owen, in allusion to the remarkable 

 spine-like bones which ran along the sides of the body and tail. A 

 number of new leaf and other forms from the plant-bed in Alum 

 Bay, Isle of Wight, were described by Mr. W. S. Mitchell, amongst 

 which were some well-preserved flowers. The interest attached to 

 these beds has induced the Association to make a grant for their more 

 complete exploration. 



It is, of course, always desirable that at all meetings of the 

 Association local geology should be well represented. On this 

 occasion the Silurian, carboniferous, and Triassic rocks and their 

 fossils, as well as the peculiarities of the superficial drifts, were 

 described by Messrs. C. Ketley, S. Bailey, H. Johnson, W. Molyneux, 

 C. Twamley, Rev. P. B. Brodie, and other local geologists. Though 

 not forming part of the proceedings of the Section, we may class 

 with these communications the lecture of Professor Jukes on the 

 extension of the coal measures below the Red Rocks of the neighbour- 

 hood of Birmingham. The chief point impressed on the audience 

 was the fact, that, though coal measures might exist at a great depth, 

 it by no means follows that after sinking through a great thickness of 

 rock any valuable beds of coal would be found. He particularly 

 insisted on the necessity of anyone who undertook such a project 



