REVOLUTIONS. 95 



considered, nor that those Avhich occur in the transition 

 limestones of Norway, Germany, and Ireland, have been 

 investigated with the view of determining the particular 

 species : And I have demonstrated that the rule does not 

 hold true, in reference to the genus, by the publication of 

 figures and descriptions of ten species of Orthoceratites, 

 from the beds of the independent coal formation *. Until 

 geologists form more accurate notions with regard to fossil 

 species, no reliance can be placed on the observations 

 which they offer respecting their geographical distribution. 

 We have no reason to doubt, that the laws which now 

 regulate the geographical distribution of animals and plants, 

 did exercise their influence at the period, when the transi- 

 tion and floetz-rocks were forming. We may, accordingly, 

 expect to find the Jbssil animals and plants of the tempe- 

 rate regions, differing as much from those in tropical coun- 

 tries, as the recent kinds are known to do. Each region 

 may be expected to exhibit a peculiar fossil Fauna and 

 Flora -f-. 



" " Observations on the Orthoceratites of Scotland," — Thomson's Annals 

 of Philosophy, for March 1815 ; where some proofs are likewise given of the 

 same fossil species, occurring in different beds of tlie same formation, and 

 even in diiferent formations. 



-)■ In the article Conchologj', in the Supplement to the Encyclopaedia Bri- 

 tannica, I have stated, •' that in every country there are particular animals 

 and vegetables, which indicate, by their mode of growth and rapid increase, a 

 peculiar adaptation'to the soil and climate of that district. Hence we find a 

 remarkable difference in the animals and plants of different countries. Many 

 shell-fish have indeed a very wide range of latitude, through which they may 

 be observed ; but we know, that the same molluscous animals which are na- 

 tives of Britain, are not found, as a whole, as natives of Spam, while the 

 molluscous animals of Africa differ from both. If the same arrangement of 

 the molluscous animals always prevailed in the different stages of their exist- 

 ence, then we may expect to find the fossil shells of one country differing as 



