▁ ▁( Original ▁description ) ▁The ▁sin ist ral ▁shell ▁is ▁thin , ▁el ong ated ▁and ▁sl ender . ▁It ▁contains ▁ 1 0 - 1 1 ▁wh or ls . ▁Its ▁color ▁is ▁light , ▁p ink ish ▁- b rown , ▁without ▁bands . ▁The ▁interior ▁of ▁the ▁a pert ure ▁is ▁a ▁little ▁l ighter : ▁The ▁upper ▁wh or ls ▁are ▁more ▁or ▁less ▁ch alk y . ▁The ▁proto con ch ▁is ▁smooth ▁and ▁ ▁infl ated . ▁The ▁later ▁wh or ls ▁are ▁convex . ▁The ▁s uture ▁is ▁deeply ▁im pressed . ▁The ▁shell ▁is ▁sculpt ured ▁by ▁fine ▁increment al ▁lines ▁and ▁on ▁the ▁last ▁wh or ls ▁a ▁few ▁obsc ure , ▁spir al ▁stri ations , ▁mostly ▁below ▁the ▁peri ph ery . ▁The ▁anal ▁fasc icle ▁is ▁trace able ▁on ▁the ▁sp ire ▁as ▁a ▁fl atten ed ▁or ▁obsc ure ly ▁gro oved ▁band . ▁The ▁a pert ure ▁is ▁narrow . ▁The ▁si ph onal ▁canal ▁is ▁wide ▁and ▁short . ▁The ▁col um ella ▁is ▁nearly ▁straight , ▁with ▁a ▁well - defined ▁call us , ▁ob liqu ely ▁trunc ate ▁below . ▁The ▁outer ▁lip ▁is ▁produced ▁and ▁deeply ▁em argin ate ▁near ▁the ▁s ut ural ▁margin ▁of ▁the ▁wh or l . ▁ ▁Distribution ▁ ▁References ▁▁ ▁Mc Le an ▁J . H . ▁( 1 9 9 6 ). ▁The ▁Pro sob ranch ia . ▁In : ▁Tax onom ic ▁Atlas ▁of ▁the ▁B