This is the first in a series of group-by-group treatments of the taxonomy and nomenclature of the molluscs of Singapore based on a review of the literature and examination of geographically relevant material. The family Angariidae is treated. Angaria delphinus is the only representative of the family to be found in Singapore. It was first recorded in 1836 as a species of Delphinula, a synonym of Angaria. A record of Delphinula turbinopsis from Singapore in 1847 is believed to be a misidentification of Turbo bruneus.

The family Trapezidae is reviewed in the second of a series of group-by-group treatments of the molluscs of Singapore. The family is represented in Singapore waters by Coralliophaga coralliophaga, Neotrapezium sublaevigatum, and Glossocardia obesa. The last-named is a first record of this species from Singapore and is based on two specimens from Pulau Jong in the Singapore Straits.

The family Donacidae in Singapore is reviewed, and the occurrence of two species, Donax (Latona) cuneata and Donax (Latona) faba, is confirmed. Donax pallidus, which was first described from Singapore, is regarded to be a junior subjective synonym of Donax (Latona) faba based on examination of photographs of a syntype and topotypic material.

The family Amathinidae is reviewed in the 4th part of a group-by-group treatment of the molluscs of Singapore. Amathina tricarinata, a gastropod that parasitises other molluscs, is the only species recorded from Singapore in the Amathinidae.

The subfamily Planaxinae, of the family Planaxidae, in Singapore is treated here. The subfamily is currently represented in Singapore by two species: Fissilabia decollatus and Planaxis sulcatus. Diagnoses, figures, records, and other information on both species are provided as part of an effort to document the diversity of the malacofauna in Singapore. Comments on the current composition of this subfamily in Singapore, as well as remarks on Monoptygma melanoides, a subjective synonym of Fissilabia decollatus, are also provided.

The family Truncatellidae in Singapore is represented by a single species, the widely-distributed Truncatella guerinii. In this review of the family, specimens of Truncatella guerinii from Singapore are figured and a diagnosis is provided to aid identification. Some notes of interest are added for information.

The freshwater snails of the family Ampullariidae in Singapore are reviewed. This family is represented in Singapore by Pila ampullacea, Pila scutata, and the introduced Pomacea canaliculata and Pomacea maculata. Pila scutata and Pomacea canaliculata were once the only known Ampullariidae species in Singapore. Here, we discuss in further detail the other two ampullariids that have only been recently confirmed to be part of the malacofauna of Singapore—Pila ampullacea and Pomacea maculata. Two other species of non-native Ampullariidae, Pomacea diffusa and Marisa cornuarietis are sold in the local aquarium trade, but have not been recorded in the wild to date.

The family Aplustridae, occurring in the waters of Singapore, is reviewed. The family is represented in Singapore waters by Hydatina albocincta and Hydatina zonata. Diagnoses, figures, records, and other information on both species are provided as part of an effort to document the diversity of the malacofauna in Singapore.

The family Argonautidae is represented in Singapore waters by Argonauta argo and Argonauta hians. The latter species is a new record for Singapore based on a recent discovery of a shell at the Semakau Landfill. Information on the records of both species in Singapore, taxonomic or nomenclatural, and other related notes of interest are provided.