pictet's paleontology. 4<7 



the more do these supposed identifications disappear ; and I firmly 

 believe that as the science advances, it will be found to have been 

 only by mistaken resemblances that the same name has been applied 

 in the catalogues to fossils of different formations. The present state 

 of palaeontology does not perhaps permit us to affirm this, but every 

 probability is in favour of the speciality of fossils. All the investi- 

 gations properly made by careful zoologists, and with the precision 

 which is now demanded of the palaeontologist, have invariably ter- 

 minated in the result, that the fossils of each formation are different. 

 The most eminent palaeontologists are now agreed with regard to this 

 fundamental fact ; and I am perfectly satisfied that we may fully 

 expect its confirmation as time advances. It was indeed natural that 

 the first observers should have been more struck with analogies than 

 differences, for a slight and superficial examination is sufficient to 

 exhibit the former, but it requires more labour to make out the lat- 

 ter ; and this indeed has been the case even with recent species, 

 ancient authors having often grouped under one name several allied 

 species, which have been since separated. With regard also to fossils 

 at one time identified, we find that afterwards more accurate or less 

 hurried observers have found differences where they had not before 

 been seen ; and hundreds of cases might be quoted in which species 

 at one time united have required separation, and have thus served 

 to demonstrate the truth of a law which they before seemed to con- 

 travene. 



" From future investigations, we shall one day learn how far this 

 law extends ; but most palaeontologists have already admitted it with 

 reference to the four great geological periods, and even for the 

 principal formations into which these have been subdivided*. Thus 

 it will hardly now be denied, that in the secondary period, the 

 fossils of the triassic, Jurassic and cretaceous formations are com- 

 pletely distinct, but it is probable that we may go still further, 

 and that the groups of strata of which these larger divisions are 

 made up also possess peculiar faunas. The best recent investiga- 

 tions seem, for instance, to show, that in the cretaceous series none 



* These are, according to our author, — 



4. Diluvial period. 



3. Tertiary period (upper, middle and lower). 



2. Secondary period (cretaceous, Jurassic, triassic and Permian). 



1. Primary period (Carboniferous, Devonian and Silurian). 

 [It may not be amiss here to refer to the recent investigations of Dr. Philippi, 

 on the Tertiaries of South Italy, translated in the present number of this Journal 

 (Part ii. p. 1) ; to the discovery by Professor Owen of the remains of existing spe- 

 cies of Mammalia in the middle tertiary deposits (see his work, now in course of 

 publication, on the British Fossil Mammalia and Birds) ; to the identification by 

 M. Deshayes of at least two species of shells common to the tertiaries and the chalk 

 (Bui. de la Soc. Geol. de Fr., 2nd Ser., vol. for 1844, June 17) ; to the probable 

 identity of the Ichthyosaurus found in the lower chalk with a common species 

 (/. communis) in the lias (Owen, Rep. of Brit. Assoc, 11th Meeting, p. 193) ; and 

 to the statement by M.de Verneuil, that of the Russian Palaeozoic fossils, as many 

 as eighteen species are common to the Permian and older formations ; or, in other 

 words, to the secondary and primary periods of M. Pictet (Gcol. Journ. vol. i. 

 p. 87).-Ed.] 



