Subject ASC000115s
The Quarterly journal of the Geological Society of London.
v.56 (1900), Page 402 (1900)
Smithsonian Libraries
BHL Page 41487752
Keywords
Thecae graptolites thecae rhabdosoma Cyrtograptus symmetricu river Irfon Ackley fossil paleontology graptolite diagram M. Flemingii shale welsh shale graptolite zone large graptolite geology Shales Welsh Borders graptolite nicholson Rhabdosoma Rhabdosoma