On the Lower Didymograptus zone (3B) at Ringsaker, and contemporaneous deposits in Scandinavia

The two upper sub-zones of the Lower Didymograptus Beds (3 b) appear in limestone-trilobite facies at Heramb, Ringsaker, Norway. The layers at Heramb correspond to the Planilimbata Limestone, or part of it, and the beds are correlated with corresponding deposits elsewhere in Scandinavia. The 3 b sediments are deposited in a more or less closed basin on the Scandinavian Foreland. In this basin the different facies of the 3 b sediments have a distinct distribution. The trilobites from the upper subzones of 3 b at Heramb are described, among them three new trilobite species:
Megalaspis ringsakerensis sp. n.
Ptychopyge herambensis sp. n.
minor sp. n.
Ampyx volborthi Schmidt is transferred to the genus Lonchodomas.