The occurrence at Plymouth of the opisthobranch Akera bullata, with notes on its habits and relationships

Akera bullata O. F. Müller is a tectibranch mollusc having a coiled external shell and a foot with lateral extensions used for swimming. At certain times of the year it swims actively, as was observed by Donovan, who writes that it ‘sports in its watery element with all the liveliness of a butterfly, and formed a pleasing object when kept alive in a glass of sea water’ (quoted by Montagu, 1803). Although sometimes abundant locally, it is not a mollusc often taken by the collector, even though it is a conspicuous object when swimming.