enders ▁Category : US ▁L us itan os ▁Saint - M aur ▁players ▁Category : S ports people ▁from ▁Y vel ines <0x0A> </s> ▁Ce phal otes ▁p all ens ▁is ▁a ▁species ▁of ▁ar b ore al ▁ant ▁of ▁the ▁genus ▁Ce phal otes , ▁character ized ▁by ▁an ▁odd ▁sh aped ▁head ▁and ▁the ▁ability ▁to ▁" par ach ute " ▁by ▁ste ering ▁their ▁fall ▁if ▁they ▁drop ▁off ▁of ▁the ▁tree ▁they ' re ▁on . ▁G iving ▁their ▁name ▁also ▁as ▁gl iding ▁an ts . ▁ ▁References ▁ ▁p all ens <0x0A> </s> ▁A ▁t et rose ▁is ▁a ▁mon os ac char ide ▁with ▁ 4 ▁carbon ▁atoms . ▁They ▁have ▁either ▁an ▁al de hy de ▁functional ▁group ▁in ▁position ▁ 1 ▁( ald ot et ros es ) ▁or ▁a ▁ ▁k et one ▁functional ▁group ▁in ▁position ▁ 2 ▁( ket ot et ros es ). ▁ ▁The ▁al dot et ros es ▁have ▁two ▁ch iral ▁cent ers ▁( as ym metric ▁carbon ▁atoms ) ▁and ▁so ▁ 4 ▁different ▁s tere ois om ers ▁are ▁possible . ▁There ▁are ▁two ▁naturally ▁occurr ing ▁s tere ois om ers , ▁the ▁en anti om ers ▁of ▁er yth rose ▁and ▁thre ose ▁having ▁the ▁D ▁configuration ▁but ▁not ▁the ▁L ▁en anti om ers . ▁The ▁k et ot et ros es ▁have ▁one ▁ch iral ▁center ▁and , ▁therefore , ▁two ▁possible ▁s tere ois om ers : ▁er yth r