▁or ▁con ca ve ▁below ▁the ▁s ut ures , ▁convex ▁and ▁sw ol len ▁at ▁the ▁peri ph ery ▁and ▁above ▁each ▁s uture . ▁They ▁are ▁enc irc led ▁by ▁numerous ▁fine ▁li ra e . ▁The ▁body ▁wh or l ▁is ▁a ▁trif le ▁def lex ed ▁at ▁the ▁a pert ure ▁and ▁is ▁often ▁sub angular ▁at ▁the ▁peri ph ery . ▁The ▁r hom bo idal ▁a pert ure ▁measures ▁less ▁than ▁half ▁the ▁total ▁length ▁of ▁shell . ▁The ▁ac ute ▁per ist ome ▁is ▁rather ▁thin , ▁and ▁ed ged ▁by ▁a ▁row ▁of ▁red ▁d ots , ▁thick ened ▁a ▁little ▁distance ▁within , ▁the ▁thick ening ▁fin ely ▁c ren ulated . ▁The ▁vertical ▁col um ella ▁is ▁marked ▁with ▁crim son ▁at ▁the ▁outer ▁base . ▁ ▁Description ▁This ▁marine ▁species ▁is ▁en demic ▁to ▁Australia ▁and ▁occurs ▁off ▁South ▁Australia ▁and ▁Tas mania . ▁ ▁References ▁▁ ▁Bra z ier , ▁J . ▁ 1 8 8 7 . ▁Tro ch idae ▁and ▁other ▁gener a ▁of ▁South ▁Australia , ▁with ▁their ▁syn onym s . ▁Trans actions ▁of ▁the ▁Royal ▁Society ▁of ▁South ▁Australia ▁ 9 : ▁ 1 1 6 - 1 2 5 ▁ ▁External ▁links ▁ ▁To ▁World ▁Register ▁of ▁Marine ▁Species ▁ ▁les ue uri ▁Category : G ast rop ods ▁described ▁in ▁ 1 8 8 0 <0x0A> </s> ▁Park ▁Jung - ba e ▁( born ▁ 1 9 ▁February ▁ 1 9 6 7 )