Acteonidae, Bullinidae and Ringiculidae (Gastropoda: Heterobranchia) from the Plio-Pleistocene of the Philippines Author Helwerda, Renate A. text Zootaxa 2015 3990 2 197 220 journal article 10.11646/zootaxa.3990.2.2 1740ec81-c55e-44ce-9a6d-cd62acd5d898 1175-5326 242947 BDF1BC11-4848-4858-99DC-0336A5FBEE2B Genus Microglyphis Dall, 1902 Type species. Actaeon curtulus Dall, 1889 (by original designation); Recent, off Magellan Strait. Remarks. Shells of this genus are similar to shells of the genus Ringicula , except that they do not develop a thickly callused aperture. This makes them difficult to distinguish from juvenile Ringicula shells, but they exhibit determinate growth characters subtly, such as a thin callus and a subtle change in coiling direction in the aperture. All adult shells of a Microglyphis species typically reach the same size as well. Burn & Thompson (1998) mention that Microglyphis shells have only one columellar fold, but, while this is the case in M. japonica ( Habe, 1952 ) , there are also species with two columellar folds, such as M. mazatlantica ( Dall, 1908 ) and M. estuarina ( Dall, 1908 ) .