394 Mr Smith on the Changes of the Level erf the Sea, 



between the SiciHan tertiaries with 95 per cent, of existing spe- 

 cies of shells and the conchiferous gravels and sands of Holder- 

 ness and Lancashire, in which, among twenty species of shells 

 now living in the German Ocean, one occurs which is not yet 

 known. If the Lancashire shells are, like those of Specton, 

 Udevalla, and the coasts of Devon and Calvados, raised beaches, 

 and to be classed in the modern epoch, why are the Sicilian 

 ranked as tertiary .?""* It appears to me that Mr Lyell has 

 solved the difficulty, by classing amongst the tertiary formations 

 " all those geological monuments which cannot be proved to 

 have originated since the earth was inhabited by man."" The 

 appearance of man on the surface of the earth is an event of 

 such transcendent importance, as to justify its being used as 

 the separating line of the recent or human period, and those 

 which preceded it. Changes of level have occurred in every 

 stage of the earth's history : those of which I have been treat- 

 ing must have taken place during that which immediately pre- 

 ceded the recent period, and, of course, the organic remains be- 

 longing to that division of the tertiary group, which he has 

 named the newer pliocene. It is of great importance that 

 every circumstance connected with this deposit should be care- 

 fully observed and recorded, as an accurate knowledge of it 

 cannot fail to throw much light on that hitherto obscure branch 

 of geology, the nature and origin of the different alluvial beds 

 which compose the earthy covering of the more ancient forma- 

 tions; and, as it must be the object of the science to proceed 

 from what is known to what is unknown, we cannot too mi- 

 nutely investigate that part of it which forms the first step in 

 the descending series, in order that we may obtain firmer foot- 

 ing in prosecuting our researches into the more remote epochs 

 of the history of the earth. t 



* Treatise on Geology, p. 263. 



+ The catalogues which accompany the memoir consist of one of the re- 

 cent marine shells in that portion of the British seas which extends from 

 the Firth of Clyde to the north coast of Ireland, containing 276 species, of 

 which five are new to the British Fauna ; and another of the fossil shells 

 described in the paper, chiefly found in the same geographical region, con- 

 taining 180 species, of which about fourteen are unknown or extinct. These 

 catalogues, with figures and descriptions of the unknown species, will we ex- 

 pect appear in a future Number, accompanied, it is hoped, by a notice from 

 M. Deshayes on the subject. 



