Below, you see a list with possible ichnogenera for a lined (sub)horizontal, unbranched burrow with a cylindrical cross section or a ridge-like appearance and passive filling. Click on them to get detailed descriptions of the ichnogenus and a list of its ichnospecies. (Please allow for pop-up windows):

• Cystichnium
• Fimbritubichnus (Ichnogenus includes ornamented ichnospecies)
• Nummipera
• Oikobesalon
• Palaeophycus (May be branched or unbranched; ichnogenus includes ornamented ichnospecies)
• Walpia

Knaust (2012) listed Biformites here. However, we agree with Schlirf (2012) that Biformites is in fact a surface trace (“imprint”).