The first family is Elysiadæ, types Limapontia and Elysia.
The second is Phyllirhoidæ, type Phyllirhoe.
The third is æolidæ, types Glaucus and Æolis.
The fourth is Tritoniadæ, types Scyllæa and Tritonia.
The fifth is Doridæ, types Idalia and Doris, the curious sea-lemon.
The first family of the second division, Tectibranchiata, is Phyllidiadæ, types Diphyllidia and Phyllidia.
The second family is Pleurobranchidæ, types, Umbrella, in form resembling a limpet, and Pleurobranchus.
The third family is Aplysiadæ, types, Dolabella and Aplysia.
The fourth family is Bullidæ, types, Scaphander, Acera, and Bulla.