Sigmoilina species, from Ponder (1974) (1, Sigmoilina sigmoidea; 2-11, other Sigmoilina species; 1-9, axial cross section; 10a, 10b, 11a, lateral view; 10c, 11b, aperture view).   
  Part of: Egloff W, Agosti D, Kishor P, Patterson D, Miller J (2017) Copyright and the Use of Images as Biodiversity Data. Research Ideas and Outcomes 3: e12502. https://doi.org/10.3897/rio.3.e12502