8 4 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



The two accompanying small Tables (III. & IV.) relate to the dis- 

 tribution of the fauna of the Lower and Upper Lingula-flags, with the 

 number of genera and species that pass to the Lower and Upper Tre- 

 madoc. Nine whole classes are unrepresented in each division ; only 

 2 classes, indeed, in either have real value, the Crustacea and Brachio- 

 poda. I regard the Annelida as being wholly doubtful, so far as 

 regards species : their presence and influence is manifest everywhere 

 through the slates and flags of the lowest Palaeozoic rocks ; but the 

 fragmentary condition of the remains, as well as the uncertainty 

 relative to their development and history, almost sets aside their 

 numerical value as species in evidence. 



In the Lower Lingula-flags the 25 species of Crustacea stand alone ; 

 and, with the exception of Hymenocaris vermicauda, Leperditia 

 HicJcsii, and Primitia solvensis, all are Trilobita. Five species, 

 all Trilobites, pass to the Upper Lingula-flags. The Upper Lingula- 

 flag table is even more significant ; for every one of the 30 species of 

 Crustacea belongs to the group of Trilobita, and only 2 species pass 

 to the Upper Tremadoc, Agnostus princeps and Ampyx prcenuntius, 

 and not one to the Arenig, from the Lingula-flags. 



The left-hand column in all the tables shows the number of genera 

 and species that pass up from the next underlying or older formation, 

 the upper figure enumerating or expressing the number of genera, 

 and the lower denoting the number of species in each class ; the 

 same plan is applied to the genera and species that pass up into the 

 several formations as the case may be, and as expressed in the head- 

 ings of the columns. The column headed classes and the two suc- 

 ceeding, marked genera and species, speak for themselves. 



Table IY. — Upper Lingula-flags. 



Pass up 

 from 



Lower 

 Lingula- 

 flags. 



Classes. 



Grenera. 



Species. 



Pass to 

 Lower 

 Tre- 

 madoc. 



Pass to 

 Upper 

 Tre- 

 madoc. 





Plantge. 













Protozoa. 













Hydrozoa. 













Actinozoa. 













Echinodermata. 















2 



2 







4 

 5 





8 



30 



4 

 4 



2 

 2 





Bryozoa „ 



1 



1 



1 





3 

 3 





5 



8 



4 

 5 



5 





Lamellibrauehiata. 













Gasteropoda. 













Pteropoda. 













Heteropoda. 













Cephalopoda. 











7 



8 





16 



41 



9 



1 



5 

 7 



