Several "groups" of Philippine Amphidromus, a genus of tropical air-breathing land snails, are easily distinguished: the Amphidromus maculiferus complex, the Amphidromus chloris complex, the Amphidromus quadrasi complex, and the Amphidromus enobaptus complex. The author here gives an overview of the respective groups: he discusses and documents them. This is followed by an alphabetical presentation and documentation of the different species. Much attention has been given to a good visual presentation of the Amphidromus and their forms on 39 colour plates. A number of taxa is only seen in the figures dispersed in the text, because no recent material was available.
Finally, a new species of Amphidromus, Amphidromus escondidus n. sp., is described from Balut Island.