Eulimidae: Hypermastus coxi (Pilsbry, 1899) (‘Cox’s urchin-snail’)

Synonym(s): coxi Pilsbry, 1899.

Typical shell-length 4.0 mm. Sexually dimorphic. Lives subtidally and offshore as an internal parasite of sand-dollars. Native. Endemic to southeastern Australia (NSW, TAS and VIC). In Tasmanian waters, this is a common species in the N; rare or absent to the S.