For Oligospira waltoni, see
https://commons.wikimedia.org/wiki/File:Naturalis_Biodiversity_Center_-ZMA.MOLL.388479-Oligospira_waltoni(Reeve,1842)-Acavidae-_Mollusc_shell.jpeg
and
https://landsnails.org/en/Gallery/Acavidae/Oligospira

Or Oligospira polei? See Naggs & Raheem, ''Sri Lankan Snails'', NHM, London at https://www.nhm.ac.uk/resources/research-curation/projects/tropical-land-snails/publications/download/english.zip
and ditto, ''An Illustrated Guide to the Land Snails of Sri Lankan Natural Forest and Cultivated Habitats''
https://www.researchgate.net/publication/322938991_An_Illustrated_Guide_to_the_Land_Snails_of_Sri_Lankan_Natural_Forest_and_Cultivated_Habitats