RECENT ADDITIONS TO ANCIENT SEDIMENTS. 361 



Schmidt (20), and he places the Lesmahago beds of Southern 

 Scotland in this position. 



4. THE DEVONIAN SYSTEM. 



The zonal method, applied with so much success to the 

 lower Palaeozoic rocks has also been utilised for the elucida- 

 tion of the smaller subdivisions of the strata of this system, 

 and our knowledge of the classification of the Devonian 

 rocks has recently advanced considerably both at home and 

 abroad. The grouping of the strata in Belgium and Ger- 

 many has long been established, but until the last few years 

 many opinions prevailed as to the order of succession of the 

 rocks of Devonshire. In 1889, Kayser, the leading autho- 

 rity upon Devonian rocks, described the results of a visit to 

 Devonshire in a paper, " Ueber das Devon in Devonshire 

 und im Boulonnais " (21), and since then Ussher has made 

 a more detailed comparison of some of the Devonian 

 rocks of South Devon with those of the European con- 

 tinent (22), thus practically commencing for Britain a 

 task which will be completed when a thorough re-mapping 

 of North and South Devon and Cornwall has been exe- 

 cuted, in accordance with the requirements of stratigraphical 

 palaeontology. 



The most important work on the Devonian rocks of the 

 European continent is the proof furnished by Kayser that 

 the stages F, G and H of Bohemia, referred by Barrande 

 to the Silurian, really belong to the Devonian system (23), 

 thereby removing a great difficulty in the correlation of the 

 lower Palaeozoic rocks of Bohemia with those of other 

 countries, for the stage E -can be shown to possess the 

 faunas of all the divisions of the Silurian system from lower 

 Llandovery to upper Ludlow. Kayser was contented to 

 refer the stages F, G and H to the lower Devonian, but 

 Freeh gives reasons for considering that lower, middle and 

 upper Devonian beds have their representatives amongst 

 these stages. His correlation of the Bohemian and other 

 Devonian beds with those of the type-deposits will be found 



