368 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 22, 



overlaps of the various formations were in course of production, as 

 broached by Professor Ramsay, it seems to me to be still more import- 

 ant to draw special attention to the gradual transitions or passages 

 between two formations, or, in other words, from the quiet burial- 

 grounds of one epoch of life into those of another. For if, through 

 the patient accumulation of well- compared data, derived from differ- 

 ent and distant regions, we can ultimately succeed in showing that, 

 though the geological record is locally broken, yet all such gaps 

 in one country can be filled up by putting together the local 

 sequences in other and numerous tracts, we shall be in a much 

 fitter condition to reason upon the hypothesis suggested by Mr. 

 Charles Darwin, as to the probability of finding, in those enormous 

 deposits of former ages (which could indeed only have been formed 

 in very long periods), any forms of life which link on one group of 

 animals to another. As a stratigraphical geologist, who has con- 

 vinced himself that the particular break of one region is often well 

 filled up by the unbroken sequences of strata in another, I will only 

 observe, that I am acquainted with many examples of such true 

 physical transitions from one formation into another, in which 

 there is not a trace of disturbance. Thus, in addition to the ex- 

 amples given by M. Giimbel, I would refer to the tract near Saalfeld, 

 where the Upper Devonian, with its very peculiar Plants, is gradu- 

 ally linked on to the Lower Carboniferous, containing very different 

 plants. 



Again, in those well-known quiet transitional deposits which 

 occur in Britain between the great natural divisions, the Silurian 

 and the Devonian *, and again between the latter and the Carbo- 

 niferous, it is an undoubted fact that, in ascending from the lower 

 to the higher beds, we ever find different genera and species of ani- 

 mals. On the other hand, we have never found in such united strata 

 an animal representing a link between two great divisions of the 

 animal kingdom. Yet, if such links, which have not yet been found 

 in existing nature, are to be detected in the ancient crusts of the 

 earth, it is in such transitional unbroken bands as these that they 

 must be specially sought for ; and as they have been very sedulously 

 examined without affording a trace of the requisite evidence, I con- 

 tend that the geological record yields no support whatever to the 

 transmutation-theory, if that theory be restricted to the examination 

 of true natural species, and be not based on those varieties which 

 man has educed by his own efforts and perseverance. 



2. Notice of a Section at Mocktree. By R. Lightbody, Esq. 



[Communicated by J. W. Salter, Esq., F.G.S.] 



A remarkable section having been recently noticed in the Aymestry 

 Limestone at Mocktree, near Leintwardine, it may be interesting to 

 record a few particulars in reference to it. 



* See Silurian System, 1839 (passim), Siluria, 2nd edit. p. 149 et seq., and 

 Memoirs published in the Quarterly Journal of the Geological Society. 



