Columbia subject headings:
Gastropoda, Fossil.
Paleontology--Carboniferous.
Paleontology--England--Somerset.
Harvard subject headings:
Gastropoda, Fossil--England--Somerset.
Paleontology--Carboniferous
Paleontology--England--Somerset.
Princeton subject headings:
Gastropoda, Fossil--England--Somerset.
Paleontology--Carboniferous.
Paleontology--England--Somerset.