Geological Collections. 389 



groups, the species being defined by the mineral structure of the beds to 

 which they are subordinate. 



All this is in harmony with the distribution of the animal kingdom in the 

 existing seas. Some animals may be found, almost indifferently, on a 

 calcareous, a sandy, or a muddy bottom, (for example, the floating Cepha- 

 lopodes ;) and the remains of ancient animals, of kindred organization, occur 

 indifferently in calcareous, siliceous, and argillaceous groups of strata. Some 

 animals have lived and propagated under the waters of a muddy shore ; the 

 remains of these occur abundantly in our secondary beds of shale. To the 

 very existence of some shells, calcareous rocks are necessary ; and, on banks 

 of mud, or moveable sand, corals, and attached zoophytes, could find no 

 proper resting place. Hence it is, that many species of shells and zoophytes 

 are chiefly characteristic of limestone strata ; and, if they exist at all in other 

 beds, have probably been drifted there by the action of marine currents. 



It follows from these remarks, that any great change in the mineralogical 

 character of a formation must also be accompanied with a corresponding 

 change in the accompanying forms of organic structure once subservient to 

 life. In this way we may explain the great difference between the organic 

 remains of the lower oolitic series of western and central England, and of 

 the contemporaneous coal formation on the Yorkshire coast. And, in the 

 same way, we may also explain an opposite fact, observed more than once 

 by Mr Murchison and myself, during our traverses through the Eastern 

 Alps, that wherever a secondary deposit of that great chain approaches the 

 mineral type with which we are familiar iri this country, it also contains an 

 imbedded group of organic remains, very nearly resembling those we have 

 been taught to regard as characteristic of the formation. 



I believe that the subject to which I am now pointing is one of interest 

 and importance ; and I know no one who could do so much justice to it as 

 Mr Lonsdale, whose admirable knowledge of recent and fossil species, and 

 of the minutest subdivisions of our secondary groups of strata, (strengthened 

 and improved as it is by the performance of the great task he has under- 

 taken, so much to the advantage of this Society,) qualifies him to compose 

 an essay which will throw the greatest light upon the physical causes affecting 

 the distribution of organized beings during the long periods of geology. — f 

 Professor Sedgwick's address to the Geological Society, 18th Feb. 1831. 



Progress of Geology in Germany and France We have, indeed, neither 



the time nor the power to slumber ; and, in spite of ourselves, we cannot 

 but partake of that forward movement by which all our neighbours are 

 borne along. The continental press teems with admirable works on every 

 department of natural history ; and our subject has obtained, to say the 

 least of it, its full share of consideration. Professor Hoffman's map, alluded 

 to in my former address, will soon be illustrated by a work which promises 

 fair to make the north of Germany once more the classic land of geology. 

 The excellent Memoirs of MM. de Beaumont and Dulrenoy, will soon be 

 followed by the Geological Map of France, — a great national work, to 

 appear, I hope, before the expiration of this year. I select these subjects, 

 not merely on account of their general importance, but because they have an 

 immediate relation to the structure of this country, and to the best labours 

 of our own body. 



The organization of the Geological Society of Paris belongs to the history 

 of the preceding year : and when we consider the incomparable collections 

 of that capital, and the illustrious naturalists who are there assembled, we 

 confidently look to this association for results which shall greatly afl^ect the 

 future history of our science. With ordinary fortune, it can hardly fail to 

 become a great central point of union, where geologists, from all the nations 

 of Europe, may, from time to time, meet together, with no rivalry but in 

 the love of truth. — Ibid. .; * 



