ANNIVERSARY ADDRESS OF THE PRESIDENT. 



219 



Table of 18 of the chief Carboniferous Genera, showing their specific 

 or numerical value through the five areas or countries named. 



Genera. 



England. 



Scotland. 



Ireland. 



Belgium. 



America. 



Occurrences. 





AUorisma (My&cites) 



6 



3 



4 





28 



41 



. _ ,. ._ 





8 







1 





2 



13 



Uliieiiy Ooal-raeasures 







9 











(6 species). 



A nrnva pagi 



10 





23 



8 



50 



Ditto (6 species). 





4 



O 



10 



±7 



7 



44 



?Astarte 









10 



1 



11 



69 







9 



"i 



Q 



36 



13 





C0n0c9.rd.ium 



6 



2 



10 



8 



13 



39 





flf pn nn nnt a 



11 



15 



15 



9 



34 



84 







7 



9 



10 



16 



11 



53 







10 



10 



12 



2 



25 



59 



3 Coal-measures. 





10 



8 



12 





5 



35 



4 Coal-measures. 





3 



2 



3 



30 



6 



44 







6 



9 



1 



3 



18 



37 



6 Coal-measures. 





10 



10 



16 



5 



27 



68 







3 



8 



7 





13 



31 



2 Coal-measures. 







2 



7 





6 



15 







1 





1 



5 



5 



14 









i 





7 





9 







106 



102 



115 



171 



222 



716 





Solenoconchia. — 6 species of Dentalium are known ; but none pass 

 above the Carboniferous Limestone. B. priscum is the only species 

 that occurs in 3 liorizons — the Calciferous Sandstones, Lower Lime- 

 stones, and Carboniferous Limestone. D. scoticum is only found in 

 the Calciferous Sandstones ; the remaining 4 belong to the Carboni- 

 ferous Limestone, and do not range higher. 



Gasteropoda. — 223 species and 29 genera, all belonging to the 

 division Holostomata of the order Prosobranchiata, constitute the 

 univalve fauna of the Carboniferous rocks. All the genera (29) and 

 202 species occur in and range through the Carboniferous Limestone ; 

 or nearly every species occurs in this horizon. 16 of the 29 genera 

 are distributed through the Carboniferous rocks of Europe and 

 America, and are therefore of zoological as well as stratigraphical 

 value. I give the following Table of these genera to accompany 

 that showing the distribution of the Lamellibranchiata (Dimyaria) ; 

 by comparison with the molluscan fauna of Europe and America 

 we may hope to obtain some clue relative to the migration and dis- 

 persion of the Itollusea from some original area. These 16 chief 

 genera are represented in England by 176 species, in Scotland by 

 90, in Ireland by 111, in Belgium (chiefly through De Koninck) by 

 176, and in the American Carboniferous rocks by nearly 200 species. 

 This generic relationship with America is important as determining 

 similarity of bathymetrical conditions, temperature, and food, and con- 

 nexion through coast-line or land now lost, 9 genera and 21 species 



