A new species and genus of the Aglajidae and the evolution of the philinacean opisthobranch molluscs

A new genus and species of the Aglajidae is described. It differs from the other members of the family in having a radula and a rudimentary gizzard, but has sensory bristles and the Yellow Gland, features unique to the Aglajidae. From all the evidence available it is suggested that the families Scaphandridae, Gastro-ppteridae, Philinidae and Aglajidae arose separately from a Cylichna-like ancestor with an oodiaulic reproductive system. It is possible that the first three families arose from a common ancestor that had developed a monaulic reproductive system, but it is equally likely that monaulism occurred independently in each family, as it has in the Aglajidae. A new family forCylichna is proposed.