, ▁the ▁Middle ▁East , ▁and ▁Asia . ▁ ▁The ▁genus ▁currently ▁contains ▁three ▁described ▁species , ▁Ford illa ▁g erman ica , ▁Ford illa ▁sib ir ica , ▁and ▁the ▁type ▁species ▁Ford illa ▁tro y ensis . ▁ ▁Description ▁Ford illa ▁are ▁small ▁b ival ves ▁with ▁val ves ▁that ▁are ▁equal ▁in ▁size ▁and ▁sub oval ▁in ▁shape . ▁ ▁In ▁size ▁Ford illa ▁spec im ens ▁reach ▁a ▁total ▁shell ▁length ▁of ▁up ▁to ▁ ▁and ▁a ▁height ▁of ▁. ▁ ▁The ▁shell s ▁are ▁com pressed ▁later ally ▁and ▁the ▁back ▁edge ▁is ▁slightly ▁bro aden ed . ▁ ▁The ▁rear ▁ad duct or ▁is ▁less ▁developed ▁and ▁smaller ▁than ▁the ▁front ▁ad duct or , ▁while ▁the ▁small ▁ped al ▁ret ractor ▁mus cle ▁scar ▁is ▁position ed ▁near ▁the ▁front ▁ad duct or ▁scar . ▁ ▁The ▁val ve ▁h ing ▁is ▁usually ▁straight ▁to ▁slightly ▁convex ly ▁cur ved ▁and ▁each ▁val ve ▁will ▁have ▁at ▁most ▁one ▁to oth ▁present . ▁The ▁external ▁surface ▁of ▁the ▁shell ▁occasionally ▁show ▁faint ▁rib bing . ▁ ▁The ▁inner ▁shell ▁layers ▁of ▁Ford illa ▁species , ▁as ▁with ▁the ▁related ▁genus ▁P oj eta ia , ▁consist ▁of ▁layers ▁of ▁carbon ate ▁which ▁is ▁a kin ▁to ▁the ▁l amin ar ▁a rag on ite ▁layer ▁found ▁in ▁ext ant ▁mon op lac op hora . ▁ ▁The ▁struct uring ▁is ▁similar ▁to ▁shell ▁layer ing ▁found ▁in ▁the ▁ext inct ▁gener a ▁An ab are lla