[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Phylum Mollusca Linnaeus, 1758 - molluscs
     Class Gastropoda Cuvier, 1795 - snails and slugs
       Family Caecidae Gray, 1850 - caecids
         Genus Caecum Fleming, 1813
           Caecum armoricum de Folin, 1869
           Caecum atlantidis Watson, 1897
           Caecum auriculatum de Folin, 1868
           Caecum clarkii Carpenter, 1859
           Caecum elegantissimum (Carpenter, 1859)
           Caecum engli (Nofroni, Pizzini & Oliverio, 1997)
           Caecum eunoi (Nofroni, Pizzini & Oliverio, 1997)
           Caecum glabrum (Montagu, 1803)
           Caecum pollicare Carpenter, 1859
           Caecum searleswoodi Carpenter, 1859
           Caecum subannulatum de Folin, 1870
           Caecum swinneni (Nofroni, Pizzini & Oliverio, 1997)
           Caecum trachea (Montagu, 1803)
           Caecum vitreum (Carpenter, 1859)