The Caenogastropoda is one of the major clades of gastropods, including the neogastropods and most of the 'mesogastropods'. Caenogastropods are primarily aquatic, including both marine and freshwater species.
Characters (from Ponder & Lindberg 1997): Ctenidium monopectinate, with skeletal rods. Simple renal lamellae in adult left renal gland. Podocytes restricted to filtration site of auricle with characteristic closed filtration chambers and histology. Euspermatozoon with subacrosomal basal plate; sperm midpiece long, with four or more mitochondria not arranged in a helical coil; paraspermatozoa with distinct head and tail tuft. Radula with two marginal teeth. Nerve ring posterior to buccal mass, salivary glands passing through nerve ring. Three or more anterior pedal nerves. Intestine with first loop short, around style sac region only; anus in anterior half of anterior pallial cavity. Faecal material produced as pellets.
Ponder, W. F., & D. R. Lindberg. 1997. Towards a phylogeny of gastropod molluscs: an analysis using morphological characters. Zoological Journal of the Linnean Society 119 (2): 83-265.
Christopher 10:50, 3 February 2011 (UTC)