previously placed in the Order: CEPHALASPIDEA, in the Subclass: OPISTHOBRANCHIA

Class : Gastropoda  Cuvier, 1797
Subclass:  Heterobranchia  J.E. Gray, 1840
informal group:  Lower Heterobranchia (Allogastropoda)  Haszprunar, 1985
according to Bouchet & Rocroi (2005) is the superfamily Acteonoidea no more in the Order Cephalaspidea

Superfamily:  Acteonoidea  d'Orbigny, 1843
Family:  Aplustridae  J.E. Gray, 1847

Hydatina physis

Micromelo undatus

Class:  Gastropoda  Cuvier, 1797
Subclass:  Heterobranchia  J.E. Gray, 1840
Clade:  Euthyneura Spengel, 1881
Superorder:  Euopisthobranchia  Jörger et al., 2010
Order:  Cephalaspidea  P. Fischer, 1883
Superfamily:  Bulloidea  J.E. Gray, 1827
Family:  Bullidae  J.E. Gray, 1827

Bulla occidentalis

Superfamily:  Haminoeoidea  Pilsbry, 1895
Family:  Haminoeidae  Pilsbry, 1895

Haminoea elegans

Haminoea succinea

Superfamily:  Philinoidea  J.E. Gray, 1850
Family:  Aglajidae  Pilsbry, 1895 (1847)

Camachoaglaja berolina	Camachoaglaja mariagordae	Chelidonura cubana	Chelidonura hirundinina	Nakamigawaia felis
Navanax gemmatus	Philinopsis pusa	Spinoaglaja anneae	Spinoaglaja petra

Family:  Gastropteridae  Swainson, 1840

Gastropteron chacmol