3 9 ▁by ▁R . ▁Bed ford ▁and ▁J . ▁Bed ford , ▁into ▁the ▁super family ▁by ▁Ok ul itch ▁in ▁ 1 9 3 7 , ▁and ▁family ▁in ▁ 1 9 6 9 ▁by ▁Ro zan ov . ▁It ▁was ▁fully ▁named ▁Se kw icy ath us ▁nah anni ensis ▁by ▁Hand field ▁in ▁ 1 9 7 1 . ▁ ▁Mor ph ology ▁▁ ▁Each ▁Arch ae ocy ath ▁is ▁distinguished ▁by ▁the ▁differences ▁in ▁the ▁internal ▁and ▁external ▁walls , ▁as ▁well ▁as ▁by ▁the ▁inter v all um . ▁S . ▁nah anni ensis ▁ ▁has ▁two ▁walls . ▁S . ▁ ▁nah anni ensis ' ▁outer ▁wall ▁has ▁horizontal ▁car c ass ▁canal ▁tub es , ▁no ▁external ▁pl ates , ▁b umps , ▁or ▁additional ▁she ath ▁on ▁the ▁external ▁structure . ▁It ▁has ▁st ip ules , ▁the ▁car c ass ▁per for ations ▁are ▁can als , ▁and ▁the ▁outer ▁wall ▁is ▁well ▁defined . ▁The ▁internal ▁structure ▁has ▁a ▁simple ▁structure , ▁with ▁por es ▁on ▁the ▁inner ▁walls , ▁and ▁no ▁st ipp ling ▁or ▁additional ▁she ath . ▁In ▁the ▁inter v all um , ▁there ▁are ▁inter v all ar ▁cells ▁and ▁sept a , ▁but ▁no ▁tab ula e . ▁S . ▁nah anni ensis ▁is ▁a ▁solit ary ▁organ ism . ▁ ▁Geographic ▁distribution ▁▁ ▁S . ▁nah anni ensis ▁ ▁is ▁found ▁in ▁Canada , ▁Europe , ▁Russia , ▁and ▁the ▁United ▁States . ▁ ▁References