Hood. 1–4 Psammothidium marginulatum (6900) 5–7 Achnanthidium duthiei [A, sp. PH] (6904) 8–13 Achnanthidium kriegeri (6900) 14 Achnanthidium minutissimum (6912) 15–17 Rossithidium petersenii (6900) 18 Cocconeis rugosa (6898) 19–22 Eucocconeis flexella (6898, 6907) 23, 24 Eucocconeis depressa (6907) 25 Nupela (?) sp. (6899) 26 Eucocconeis alpestris (6909) 27, 28 Eucocconeis laevis (6909). Scale bar: 10 µm.