There is no penial appendix, no vagina, which means that penis, oviduct and spermatheca duct join at a common point.

[2] These are closely allied species, in which the internal organization is in many cases more distinctive than the external aspect of the shell.

[3] These species occur in North America, Greenland, Europe and northern Asia.

Kurzes Verzeichnis der bis jetzt in unserm Vaterlande entdeckten Conchylien.

Naturwissenschaftlicher Anzeiger der Allgemeinen Schweizerischen Gesellschaft für die Gesammten Naturwissenschaften, 3 (11): 83–90; (12): 91–94.