Watson described nine species of shelled opisthobranch molluscs from the Madeira Archipelago in 1897. Type material for six of these species, Diaphana flava, Pyrunculus spretus, Melanochlamys maderensis, Philine complanata, Philine trachyostraca and Berthella dautzenbergi has been located in the collections of The Natural History Museum, London and the National Museum of Wales. This material is redescribed here and lectotypes are designated for five of the species. Non-type specimens of another of Watson's species, Philine desmotis, were also found. All of these seven species are here illustrated by scanning electron microscopy for the first time.
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