ANNIVERSARY ADDRESS OP THE PRESIDENT. 



221 



Geographical Distribution of the Gasteropoda through 

 16 characteristic Genera. 





England. 



Scotland. 



Ireland. 



Belgium. 



America. 



Occurrences. 





6 



5 



8 



13 



22 



54 





3 



3 



4 



15 



2 



27 





20 



17 



20 



20 



23 



100 





2 



1 





2 





5 





17 



8 



12 



5 



i*9 



61 





12 







5 



2 



19 





15 



7 



"& 



19 



20 



67 





13 



9 



9 



14 



16 



61 





2 



1 



3 







6 



Patella 



7 





5 



6 





18 





4 





3 





2 



9 





5 



"2 



4 



"i 



4 



16 





46 



24 



16 



59 



65 



210 



Turritella 



6 



1 



4 





2 



CO 





6 



1 



4 



"5 





16 





12 



11 



13 



12 



20 



68 





176 



90 



111 



176 



197 



750 



Pteropoda. — The genus Conularia first appears in the Carboni- 

 ferous rocks in the Lower Limestone Shale, and ranges through all 

 but the Upper Coal-measures. This genus dies out in the Coal- 

 measures. Many of the nodules in the " Penny-stone " of Coal- 

 brookdale contain fine examples of O. quadrisidcata, Sow., the only 

 determined species known. An undetermined species occurs in the 

 Calciferous Sandstones of "Woodhall, Scotland. America yields 17 

 species of Conularia to our 2 ; our C. quadrisulcata is not known 

 out of Britain. 



Heteropoda. — Bellerophon and Porcellia (the former with 27 

 species and the latter 4) exhaust the species in the Carboni- 

 ferous rocks. At no period in Palaeozoic times did so many species 

 of Bellerophon exist in one horizon. 24 of the 27 species are 

 found in the Carboniferous Limestone ; and 6 of these 24 species 

 range higher ; they are : — Bellerophon apertus, Sow. ; B. decussatus, 

 Flem. ; B. Dumonti, D'Orb. ; B. hiulcus, Mart. ; B. Oldhamii, Portl. ; 

 and B. Urii, Flem. 4 species (B. costatus, Sow., B. decussatus, 

 Flem., andvar. undatus, Ether., and B. Urii, Flem.) are Calciferous 

 or Tuedian species. B. decussatus, B. apertus, B. hiulcus, and B. Urii 

 range up to the Middle Coal-measures. 5 species occur in the 

 Lower Limestone Shale ; but none are peculiar to those beds. 17 

 species are essentially Carboniferous Limestone. The Yoredale 

 beds have yielded 4 species — B. apertus, B. decussatus, B. hiulcus, 

 and B. Urii, all species having a long range. The Millstone 



