ANNIVEESAET ADDRESS OF THE PRESIDENI. Ivii 



lelism can be established bet-ween them, although they all belong- 

 to the same period of time, during the deposition of the Silurian 

 system. 



The author then gives a table showing the vertical distribution of 

 57 Upper Silurian species which have been recognized as identical 

 in the two countries, and shows that out of this number belonging 

 to the " faune troisieme," 32 had already existed in the lower divi- 

 sion, or "faune seconde," of England, whereas none of them are found 

 in the " faune seconde " of Bohemia ; this fact alone he considers 

 sufficient to prove the possibility of his colonies, as these 32 species 

 coexisting with the " faune seconde" of Bohemia might have immi- 

 grated into the Bohemian basin and have dwelt there temporarily 

 during the existence of this fauna. Of these 57 species, 50 occur in 

 the AVenlock beds and 27 extend into the Ludlow beds, whereas in 

 Bohemia 51 of them are found in the etage E, and only 12 appear 

 in etage F ; only five extend into etage G and one into H. Thus 

 showing that etage E contains almost all the palDcontological con- 

 nexions hitherto recognized between the " faune troisieme " of Eng- 

 land and Bohemia, whereas the few identities occurring in the 

 three etages E, G, and H, merely serve to show that they are really 

 constituent parts of the same Tipper Silurian division. 



After describing the different connexions between the " faune 

 troisieme " of Bohemia and the other countries mentioned above, the 

 author observes that these comparative statements are the only 

 means available for ascertaining how far the last phase of the Bohe- 

 mian " faune troisieme " contained in the etages G and H is repre- 

 sented in other countries. By way of comparison, he enounces the 

 chief distinctive characters of this phase as follows : — 



1. Intermittent or sporadic presence of fish, and particularly the 

 armoured type, the first appearance of which belongs to etage E. 



2. Predominance of the genera Dalmanites and Bronteus amongst 

 the Trilobites, and the presence of the genus Calymene. The genus 

 Dalmanites is only represented by the group of I). Hausmanni. 



3. The reappearance and relatively new development of the nau- 

 tiliform Cephalopods generally, and particularly of the genera Phrag- 

 moceras and Oomplioceras, characterized by their contracted opening. 



4. Development of the group of Nautilina, representing the genus 

 Goniatites, which made its first appearance in the etage E. 



5. Sporadic appearance of Gardiola retrostriata in the etage H. 

 These characters are nowhere found all together in any horizon of 



the Upper Silurian division in the Palaeozoic regions of the two con- 

 tinents ; but their absence shows itself in very difterent degrees in 

 the different countries compared with Bohemia. In the neighbour- 

 ing regions of Saxony, Thuringia, and Eranconia no trace has hitherto 

 been found of the last phase of the " faune troisieme," whereas the 

 earher phase has now been distinctly recognized. The Silurian 

 deposits of these regions appear to belong to the great Palaeozoic 

 zone of the north, as England, Russia, and the Harz, the faunas of 

 which, notwithstanding their greater distance, bear a very marked 

 resemblance to the phase of the etages G and H. Sweden and Nor- 



