AcastocephalaAcastocephala is a genus of trilobites from the middle Silurian, known from the United Kingdom.EtymologyThe name is derived from the genus Acaste and the Ancient Greek κεφαλή "head", indicating the headshield is similar to Acaste.TaxonomyAcastocephala may contain the ancestor of Acastava.DistributionAcastocephala macrops occurs in the Middle Silurian of the United Kingdom.Acastocephala dudleyensis has been found in the Middle Silurian of the United Kingdom.