The anatomy of Gegania valkyrie powell (Mollusca: Hetrogastropoda: Mathildidae) with notes on other heterogastropods

The animal of Gegania valkyrie Powell (Mathildidae) is described and compared with previous accounts of mathildid animal features. Theacrembolic proboscis of Gegania valkyrie is compared with that of Architectonica reevei (Hanley) and Philippia (Psilaxis) oxytropis A. Adams (Architectonicidae),and these three are compared briefly with that of Triphoridae. It is shown that, contrary to most accounts, Architectonica Roeding, Philippia Gray (s.s.) and Psilaxis Woodring aU have a central tooth in the radula. The origin of the Heterogastropoda is discussed, and it is suggested that the order is probably best placed in the Opisthobranchia.