150 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



and species are also so-called Llandovery ; or out of 91 genera and 

 240 species known in the Upper Llandovery, the above 45 genera 

 and 104 species occur in the lower group also. Only 16 genera and 

 101 species are therefore really Lower Llandovery. 



Table XL — Lower Llandovery. 



Classes. 



Plantas 



Protozoa 



Hydrozoa 



Actinozoa 



Echinodermata 



Annelida 



Crustacea 



Bryozoa 



Brachiopoda 



Lamellibranchiata . 

 Gasteropoda ........ 



Pteropoda 



Heteropoda 



Cephalopoda 



3 

 7 



12 

 2 

 2 



13 

 2 



10 

 3 

 9 

 1 

 1 

 3 



3 

 50 

 26 



2 



3 

 25 



5 

 59 



3 

 13 



1 



6 



Geographical Distribution. 



68 204 



Upper Llandovery, or May-Hill Group. 



Perhaps no formation in the Lower Palaeozoic series is more diffi- 

 cult to understand, either physically or zoologically, than the " Upper 

 Llandovery," or May-Hill group. Its place, stratigraphically, was 

 long ago settled by Sedgwick, who was the first to point out the 

 necessity for separating these beds from the Lower Silurian (his 

 Cambrian), and removed them from the Caradoc in 1853, proposing 

 the name of the " May-Hill Sandstone " for these beds, being above 

 all his Cambrian Rocks ; and this is so throughout the northern 

 hemisphere. 



On the west flank of the Malverns, at Woolhope, May Hill, and 



