is the type genus of the Atlantidae
, containing all but two of the monospecific genera (Protatlanta
) in the family. The shell and keel are calcareous. The larval shell is retained following metamorphosis, becoming the spire in the adult shell. All of the nineteen species but one, A. californiensis
, dwell in tropical and subtropical waters. The majority of species (ten) are cosmopolitan and, among the remaining nine species, five are Indo-Pacific, two are restricted to the Pacific Ocean, one is Indo-Atlantic, and one is limited to the Atlantic Ocean.
An atlantid with:
- Shell and keel calcareous
- Larval shell becomes the spire in the adult shell