ural ▁dent ition ▁is ▁with ▁very ▁large , ▁strong ▁par iet al ▁l am ella , ▁one ▁pal atal ▁l am ella , ▁one ▁large ▁bas al ▁l am ella , ▁one ▁strong ▁col um ell ar ▁l am ella ▁and ▁one ▁small ▁sup rac ol um ell ar ▁l am ella . ▁Um bil icus ▁is ▁widely ▁open ▁and ▁shall ow . ▁ ▁The ▁width ▁of ▁the ▁shell ▁is ▁ 5 . 6 – 5 . 8   mm . ▁The ▁height ▁of ▁the ▁shell ▁is ▁ 3 . 2 – 3 . 3   mm . ▁ ▁No ▁live ▁spec im ens ▁have ▁been ▁found ▁as ▁of ▁its ▁type ▁description ▁in ▁ 2 0 1 7 . ▁ ▁Similar ▁species ▁Per rott et ia ▁h ong th inha e ▁diff ers ▁from ▁Per rott et ia ▁d ug ast i ▁in ▁having ▁a ▁single ▁par iet al ▁l am ella , ▁a ▁strong ▁higher ▁bas al ▁l am ella , ▁and ▁a ▁rect angular ▁a pert ure ▁with ▁rounded ▁angles . ▁ ▁Comp ared ▁to ▁Per rott et ia ▁mess ager i , ▁the ▁Per rott et ia ▁h ong th inha e ▁has ▁a ▁smaller ▁shell ▁with ▁weak ▁trans verse ▁rid ges , ▁and ▁the ▁body ▁wh or l ▁moder ately ▁expanded . ▁ ▁Comp ared ▁to ▁its ▁con gen ers ▁from ▁Vietnam ▁( Per rott et ia ▁aber r ata , ▁Per rott et ia ▁da ed alus , ▁Per rott et ia ▁g ude i , ▁Per rott