Cycloneritimorpha

Cycloneritimorpha (nerites and false-limpets) is a clade of land snails, freshwater snails, and sea snails. These are gastropod molluscs within the larger clade Neritimorpha. 14 of the families in the clade are extant, and eight of the families are extinct. According to the Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005), as well as the Cycloneritimorpha, the clade Neritimorpha also contains the (entirely fossil) clade Cyrtoneritimorpha, plus a number of other fossil families that are currently unassigned. The earliest evolutionary forms of Cycloneritimorpha show double visceral organs, double gills, and normally a double-chambered heart. The taxonomy of Cycloneritimorpha is based on work by Kano et al. (2002), that recognizes 4 clades. These clades are established on genetic analysis (28S rRNA) of recent species only. These clades proposed by Kano are ranked as superfamilies in taxonomy of the Gastropoda (Bouchet & Rocroi, 2005). The spelling of Cycloneritimorpha has been amended to the order Cycloneritida in the new taxonomy of the Gastropoda by Bouchet and Rocroi in 2017