Maryland Geological Sukvey 75 



vonian group of other countries. And for some years I have been aware 

 that, whilst our sections representing the succes.sion of the mineral masses 

 were correct, the interpretation or synonymy to be attached to the lower 

 division Avas erroneous 



" It is, however, satisfactory to have ascertained in a recent visit to my 

 old ground, that all the knowledge acquired in the fourteen years which 

 have elapsed since our survey was made, has but led to a much more com- 

 plete identification 'of the Ehenish provinces with Devonshire, than that 

 which was proposed by my colleague and self. In short, it now appears 

 that not some only, as we thought, but all the palaeozoic strata of Devon 

 have their equivalents on the banks of the Ehine. So, that, starting from 

 the North Foreland of the British Channel, and ascending into the heart 

 of the culm-fields, .... the geologist has before him the successive rep- 

 resentatives of the Ehenish deposits. 



"Those persons who may refer back to the sixth volume of the Geo- 

 logical Transactions of London, will, therefore, understand that all the 

 Ehenish ground which is described or colored in the map and sections as 

 Upper Silurian, is now embodied in the Devonian rocks; whilst to their 

 admirable description of the fossils MM. d'Archiac and de Verneuil have 

 but to add the one plate of the few so-called Silurian fossils, to their 

 thirteen plates of true Devonian types, and all the general features of our 

 labors will be in harmony with subsequent observations " (pp. 346-366) . 



As has been seen, a proper understanding of the Devonian faunal suc- 

 cession requires that its study should begin in the Ehineland and Devon- 

 shire. At the same time, if one is to learn the basis on which the Germans 

 subdivide their Devonian System of formations into Lower Devonian, or 

 Paleodevonian as it is now often called, familiarity with the results of their 

 labors must first be acquired. 



In regard to the Lower Devonian of the Ehine, Kayser states : 



" This consists of at least 10,000 feet of sandy and clayey beds, almost 

 entirely free from lime. The fossils which occur in it are almost always 



mere stone-casts They are generally rare and are found only in 



isolated beds, whicli are often separated by nuiiiy hundred feet of i)racti- 

 cally unfossiliferous rock. The fauna consists chiefly of Brachiopoda. 



