Larvae with three and four chaetigerous segments and also an early post-larval stage of Arenicola marina are described with figures. These are all bottomdwelling stages enclosed in mucous tubes and were collected from the pebble and Fucus zone at Whitstable.

The rinding of these larvae furnishes additional evidence for the view that, except when migrating in the water to new habitats, the lugworm possesses no pelagic larval stage in its life history.