Additional information is given about Hemicyclaspis kiaeri Heintz collected from the Ringerike Sandstone at Jeløya in 1954. H. kiaeri is in many respects very similar to H. murchisoni but possibly represents an independent species. The Ringerike Sandstone at Jeløya is less mighty than that at Ringerike. At Jeløya the border between the marine Silurian deposits and the continental Ringerike Sandstone is found only a few metres below sea-level. The fossiliferous beds at Jeløya belong to Lower Downtonian and are much younger than the agnathe-bearing beds at Ringerike.