Velutinidae

Velutinidae is a family of small sea snails, marine gastropod molluscs in the clade Littorinimorpha.
The shell of these animals is very thin and delicate, and internal, completely covered by the mantle (which has fused lobes) so the appearance of these animals more closely resembles that of sea slugs rather than sea snails.
Taxonomy
The following two subfamilies were recognized in the taxonomy of Bouchet & Rocroi (2005):
Subfamily Velutininae J. E. Gray, 1840 - synonyms: Marseniidae Leach in Gray, 1847; Marsenininae Odhner, 1913; Capulacmaeinae Golikov & Gulbin, 1990; Onchidiopsinae Golikov & Gulbin, 1990 (n.a.); Marseniopsidae Badel, 1993 (n.a.)
Subfamily Lamellariinae A. D. d'Orbigny, 1841 - synonyms: Coriocellidae Troschel, 1848; Sacculidae Thiele, 1929 (inv.); Pseudosacculidae Kuroda, 1933
Genera
Genera within the family Velutinidae include:
Calyptoconcha
Calyptoconcha pellucida A. E. Verrill, 1880 - translucent lamellaria
Cartilagovelutina Golikov & Gulbin, 1990
Cartilagovelutina beringensis (Derjugin, 1950)
Cartilagovelutina chondrina (Bartsch in Derjugin, 1950)
Cartilagovelutina cristata (Derjugin, 1950)
Ciliatovelutina Golikov & Gulbin, 1990
Cilifera Golikov & Gulbin, 1990
Coriocella Blainville, 1824
Echinospira Krohn, 1853
Lamellaria G. Montagu, 1815
Lamellariopsis Vayssière, 1906
Limneria H. Adams & A. Adams, 1851
Marseniella Bergh, 1886
Marseniella borealis Bergh, 1886
Marsenina Gray, 1850
Marseniopsis Bergh, 1886
Mysticoncha Allan, 1936
Onchidiopsis Bergh, 1853
Onchidiopsis glacialis M. Sars, 1851 - icy lamellaria
Onchidiopsis latissima Odhner, 1913
Onchidiopsis spitzbergensis Jensen, in Thorson, 1944
Piliscus Lovén, 1859
Piliscus commodus Middendorff, 1851
Piliscus rostratus (Golikov & Gulbin, 1990)
Piliscus undulatus (Golikov & Gulbin, 1990)
Pseudosacculus Hirase, 1928
Pseudotorellia Warén, 1989
Pseudotorellia fragilis Warén, 1989
Torellivelutina McLean, 2000
Velutina Fleming, 1820
Velutina plicatilis (Müller, 1776)
Velutina schneideri Friele, 1886
Velutina velutina (Müller, 1776)
Subfamily Lamellariinae A. D. d'Orbigny, 1841
Subfamily Velutininae Gray, 1840
Genera brought into synonymy
Capulacmaea M. Sars, 1859 : synonym of Piliscus Lovén, 1859
Chelinotus Swainson, 1840: synonym of Coriocella Blainville, 1824
Cryptocella H. Adams & A. Adams, 1853: synonym of Lamellaria Montagu, 1815
Marsenia Oken, 1823: synonym of Lamellaria Montagu, 1815
Marvillia [sic]: synonym of Limneria H. Adams & A. Adams, 1851
Morvillia Gray, 1857: synonym of Limneria H. Adams & A. Adams, 1851
Oithonella Mörch, 1857: synonym of Marsenina Gray, 1850
Oncidiopsis [sic]: synonym of Onchidiopsis Bergh, 1853
Pilidium Middendorff, 1851: synonym of Piliscus Lovén, 1859
Pseudoacculus [sic]: synonym of Pseudosacculus Hirase, 1928
Sacculus Hirase, 1927: synonym of Pseudosacculus Hirase, 1928
Velutella Gray, 1847: synonym of Velutina Fleming, 1820
References
Sources
Philippe Bouchet, Rocroi J.P., Hausdorf B., Kaim A., Kano Y., Nützel A., Parkhaev P., Schrödl M. & Strong E.E. (2017). Revised classification, nomenclator and typification of gastropod and monoplacophoran families. Malacologia. 61(1-2): 1-526.
External links
WoRMS official family page
Sea Slug Forum info
Taxa named by John Edward Gray