Columbia subject headings:
Harvard subject headings:
Beyrichiacea.
Ostracoda, Fossil.
Paleontology--England.
Paleontology--Great Britain
Paleontology--Ordovician
Paleontology--Wales.
Princeton subject headings:
Beyrichiacea.
Ostracoda, Fossil.
Palaeocopida.
Paleontology--Great Britain.
Paleontology--Ordovician.