O R D O V I C I A N - S I L U R I A N A N D L O W E R D E V O N I A N G R A P T O L I T E B E A R I N G B E D S F R O M V I E T N A M

Abstract

The present paper gives an account of the im portant Ordovician - Silurian and Lower Devonian graptolite zones and horizons of the newly discovered graptolite fauna.Based on these species and forms, a primitive Ordovician - Silurtian and Lower Devonian graptolite sequence in V ietnam is configured. It allows the au th o r to review the recently established stratigraphical units