▁the ▁pen ult imate ▁turn . ▁In ▁addition ▁to ▁the ▁ax ial ▁rib s ▁the ▁wh or ls ▁are ▁marked ▁by ▁four ▁very ▁broad , ▁low ▁spir al ▁c ords , ▁which ▁are ▁separated ▁by ▁mere ▁inc ised ▁lines ▁between ▁the ▁s ut ures . ▁This ▁rend ers ▁their ▁j unction ▁with ▁the ▁ax ial ▁rib s ▁very ▁strongly ▁nod ul ous . ▁The ▁s ut ures ▁are ▁con str icted , ▁showing ▁a ▁portion ▁of ▁the ▁peri pher al ▁cord . ▁The ▁peri ph ery ▁of ▁the ▁body ▁wh or l ▁is ▁marked ▁by ▁a ▁strong , ▁well ▁rounded ▁spir al ▁cord . ▁The ▁base ▁of ▁the ▁body ▁wh or l ▁is ▁decided ly ▁at ten u ated . ▁It ▁is ▁marked ▁by ▁seven ▁sub equal ▁spir al ▁c ords , ▁the ▁spaces ▁between ▁which ▁are ▁marked ▁by ▁numerous ▁sl ender , ▁ax ial ▁threads . ▁The ▁a pert ure ▁is ▁el ong ate - ov ate , ▁and ▁decided ly ▁eff use ▁anterior ly . ▁The ▁posterior ▁angle ▁ac ute . ▁The ▁outer ▁lip ▁is ▁thin , ▁showing ▁the ▁external ▁sculpt ure ▁within . ▁It ▁is ▁rendered ▁sin uous ▁by ▁the ▁spir al ▁c ords . ▁The ▁col um ella ▁is ▁long , ▁moder ately ▁strong , ▁somewhat ▁sin uous , ▁reflected , ▁rein for ced ▁by ▁the ▁base , ▁and ▁provided ▁with ▁a ▁fol d ▁at ▁its ▁insert ion . ▁ ▁Distribution ▁The ▁type ▁species ▁was ▁found ▁in ▁the ▁Pacific ▁Ocean ▁off ▁San ▁Pedro ▁Bay , ▁California . ▁ ▁References