Scheme of the mirror-symmetric, mantle-offset, brevisslit raphe system in frustule of the genus Eunotia Ehrenb. A valve view, different parts of valve. TA – transapical axis. Central part – between the arrows, middle part – between upper and double arrows, the beginning of valve pole – double arrow B girdle view, arrow – central raphe pore C, D raphe system without terminal fissures C arrow – a pore outer at distal end of slit, that finishes at the middle of valve pole D arrow – a funnel-like outer at distal end of slit, that finishes at the venral corner of valve pole E, F raphe system with terminal fissures – dotted lines between arrows, arrow – distal end of a slit E double arrow – the end of terminal fissure F double arrow – lacuna at the end of terminal fissure. (Original by L. Bukhtiyarova)