Larger Cnidaria and Ctenophora from the plankton and pleuston in Belgian waters

This note describes the occurrence of two species of Hydrozoa Siphonophora , six species of Scyphozoa and two species of Ctenophora that have been observed alive in Belgian waters. From a further species of the pleuston, Velella velella ( Hydrozoa Athecata ), only the skeletons, washed ashore, are known. For the more common species of Scyphozoa attention is paid to the seasonal pattern of occurrence.