A study of type and newly collected material of the Silurian ostracod Richteria migrans (Barrande, 1872) demonstrates that it had wide distribution, occurring in at least the Czech Republic, France, Sardinia, Wales, central Asia and probably Poland. R. migrans has biostratigraphic value, as an indicator for the mid to late part of the Ludlow Series. It was almost certainly pelagic, living predominantly in probable shelf topographic lows to marginal/off-shelf environments, characteristically with cephalopod-graptolite-bivalve-dominant associates. It had at least five to six growth stages, exhibits polymorphic variation, and its morphology provides evidence to endorse the notion that ‘entomozoaceans’ are myodocopes.