▁and ▁hy po con id ), ▁four ▁l oph s ▁( met al oph id , ▁mes ol oph id , ▁hyp ol oph id , ▁and ▁poster ol oph id ) ▁and ▁three ▁valle ys . ▁Each ▁of ▁the ▁lower ▁che ek te eth ▁la cks ▁an ▁additional ▁l oph , ▁the ▁e ct ol oph id , ▁which ▁is ▁present ▁in ▁A rik are e om ys . ▁The ▁p 4 ▁is ▁larger ▁than ▁any ▁of ▁the ▁mol ars ▁and ▁longer ▁than ▁it ▁is ▁wide . ▁Among ▁the ▁mol ars , ▁m 1 ▁and ▁m 2 ▁do ▁not ▁differ ▁appreci ably ▁from ▁each ▁other ▁and ▁are ▁a ▁little ▁wider ▁than ▁they ▁are ▁long , ▁while ▁m 3 ▁is ▁a ▁little ▁smaller ▁and ▁its ▁back ▁side ▁is ▁more ▁rounded ▁and ▁nar ro wer . ▁Syn cl ine ▁IV , ▁which ▁is ▁located ▁at ▁the ▁back ▁of ▁the ▁to oth , ▁between ▁the ▁hyp ol oph id ▁and ▁poster ol oph id , ▁is ▁closed ▁at ▁the ▁marg ins ; ▁this ▁valley ▁is ▁open ▁in ▁M ega pe om ys ▁b ob w il son i . ▁Syn cl ine ▁IV ▁also ▁opens ▁into ▁the ▁cent r ally ▁located ▁syn cl ine ▁III ; ▁this ▁opening ▁is ▁absent ▁in ▁A rik are e om ys . ▁There ▁are ▁two ▁roots ▁under ▁p 4 ▁and ▁three ▁under ▁each ▁of ▁the ▁mol ars , ▁fewer ▁than ▁in ▁M ega pe om ys ▁b ob w il son i , ▁which ▁shows ▁three ▁under ▁p 4