AcastoidesAcastoides is an extinct genus of trilobite that lived during the Silurian and Devonian. It has been found in Bolivia, France, Morocco, Poland, Turkey and the United Kingdom.DistributionA. constricta is found in the Silurian of the United Kingdom.TaxonomySpecies previously assigned to ''Acastoides''A. verneuili = ''Calmonia terrarocenai''