NOTES TO BOOK XVIII. 679 



brought from Riga by Sir R. Murchison was in this way 

 ascertained by Mr. Owen to belong to a fish of the genus 

 Dendrodus. (Geology of Russia, i. 67.) 



(A A.) p. 565. Mr. Lyell (B. i. c.iv.) has quoted with 

 approval what I had elsewhere said, that the advancement 

 of three of the main divisions of geology in the beginning 

 of the present century was promoted principally by the 

 three great nations of Europe, the German, the Eng- 

 lish, and the French; Mineralogical Geology by the Ger- 

 man school of Werner ; Secondary Geology by Smith 

 and his English successors : Tertiary Geology by Cuvier 

 and his fellow-labourers in France. 



(BA.) p. 587. The extension of geological surveys, the 

 construction of geological maps, and the determination of 

 the geological equivalents which replace each other in 

 various countries, have been carried on in continuation of 

 the labours mentioned in the text, with enlarged activity, 

 range, and means. It is estimated that one-third of the 

 land of each hemisphere has been geologically explored; and 

 that thus Descriptive Geology has now been prosecuted so 

 far, that it is not likely that even the extension of it to 

 the whole globe would give any material novelty of aspect 

 to Theoretical Geology. The recent literature of the 

 subject is so voluminous that it is impossible for me to 

 give any account of it here ; very imperfectly acquainted, 

 as I am, even with the English portion, and still more, 

 with what has been produced in other countries. 



While I admire the energetic and enlightened labours 

 by which the philosophers of France, Belgium, Germany, 

 Italy, Russia, and America, have promoted scientific geo- 

 logy, I may be allowed to rejoice to see in the very phrase- 

 ology of the subject, the evidence that English geologists 



