ata ▁Gray , ▁ 1 8 3 8 ▁| ▁sub div ision _ ran ks ▁= ▁Species ▁| ▁sub div ision ▁= ▁See ▁text ▁| ▁display _ par ents ▁= ▁ 3 ▁}} Dr ill ia ▁is ▁a ▁genus ▁of ▁small ▁sea ▁sn ails , ▁marine ▁g ast rop od ▁m oll us ks ▁in ▁the ▁family ▁Dr illi idae . ▁ ▁General ▁characteristics ▁The ▁shell ▁is ▁t urr ic ulated , ▁with ▁an ▁elev ated ▁sp ire , ▁longitud inal ▁rib s , ▁and ▁usually ▁revol ving ▁st ria e . ▁The ▁spir al ▁sculpt ure ▁of ▁the ▁shell ▁is ▁rather ▁smooth ▁or ▁shows ▁a ▁wide ▁spacing ▁of ▁inc ised ▁lines . ▁The ▁body ▁wh or l ▁is ▁usually ▁short . ▁The ▁col um ella ▁has ▁a ▁posterior ▁call us . ▁The ▁outer ▁lip ▁is ▁thick , ▁but ▁not ▁var ic ose , ▁nor ▁dent ate ▁within , ▁flex uous , ▁with ▁a ▁well - mark ed ▁posterior ▁anal ▁sin us ▁near ▁( but ▁not ▁reaching ) ▁the ▁s uture , ▁and ▁an ▁anterior ▁con str iction ▁or ▁sin u os ity . ▁The ▁ ▁si ph onal ▁canal ▁is ▁short , ▁cur ved ▁and ▁usually ▁narrow . ▁Some ▁species ▁show ▁an ▁interrupted ▁p ink ▁band ing . ▁ ▁The ▁animal ▁has ▁tent acles ▁approaching ▁at ▁their ▁bases ▁and ▁eyes ▁near ▁their ▁extrem ities . ▁ ▁Species ▁Species ▁within ▁the ▁genus ▁Dr ill ia ▁include : ▁▁ ▁Dr ill ia ▁ac ap ul c ana ▁( L owe , ▁ 1 9