, ▁or ▁pattern ed ▁in ▁various ▁ways . ▁The ▁proto con ch ▁is ▁pau cis p iral . ▁The ▁lip ▁of ▁the ▁shell ▁is ▁thick ened , ▁and ▁can ▁be ▁smooth ▁or ▁d entic ulate . ▁An ▁external ▁var ix ▁may ▁be ▁present ▁or ▁absent , ▁a ▁si ph onal ▁not ch ▁may ▁be ▁present ▁or ▁absent . ▁The ▁col um ella ▁may ▁have ▁ 2 - 6 ▁p lications . ▁The ▁oper cul um ▁is ▁absent ▁in ▁this ▁family . ▁ ▁Gener a ▁Ab bre vi ations ▁and ▁convent ions : ▁ ▁( M ) ▁- ▁original ▁design ation ▁by ▁monot ype ▁ ▁O D ▁- ▁ ▁original ▁design ation ▁ ▁O D ▁( M ) ▁- ▁original ▁design ation ▁as ▁type ▁species , ▁but ▁also ▁monot yp ic ▁ ▁SD ▁- ▁subsequent ▁design ation ▁as ▁type ▁ ▁SD ▁( M ) ▁- ▁subsequent ▁design ation ▁as ▁type ▁species , ▁but ▁also ▁monot yp ic ▁ ▁T ▁- ▁original ▁design ation ▁by ▁t aut onomy ▁ ▁In ▁the ▁system atic , ▁the ▁following ▁sequence ▁is ▁used ▁for ▁each ▁generic ▁syn onym : ▁ ▁Gen us ▁in ▁original ▁combination , ▁followed ▁by ▁author , ▁year , ▁page ▁number ( s ) ▁ ▁Design ation ▁ ▁of ▁type ▁species ▁followed ▁by ▁author , ▁year , ▁page ▁number ( s ) ▁ ▁Reference ▁only ▁to ▁Type ▁species ▁ ▁Mar gin ell idae ▁F lem ing , ▁ 1 8 2 8 : 3 2 8 ▁ ▁Sub family ▁Gran ul in inae : ▁This ▁sub