"Selected morphological features in the test of zonal assemblages of Echinocorys scutata Leske from the upper Chalk of Berkshire, Buckinghamshire, Hampshire, and Wiltshire, have been examined and measured. The results suggest that the changes observed in these characters at certain levels in the Chalk would have made Echinocorys more suited to a burrowing or partially burrowing habit. These adaptations are associated with lithological indications of shallow water deposition. It is suggested that the shallowing of the sea was the environmental stimulus behind the adaptations towards a burrowing mode of life."