The earliest evolutionary forms of Cycloneritimorpha show double visceral organs, double gills, and normally a double-chambered heart.[3]
Taxonomy
The taxonomy of Cycloneritida is based on work by Kano et al. (2002)[4] 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 the 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 [5]
^Kano Y., Chiba S. & Kase T. 2002. Major adaptive radiation in neritopsine gastropods estimated from 28S rRNA sequences and fossil records. Proceedings of the Royal Society of London, B, 269: 2457-2465.
^Philippe Bouchet & Jean-Pierre Rocroi, Revised Classification, Nomenclator and Typification of Gastropod and Monoplacophoran Families; Malacologia, 2017, 61(1–2): 1–526