The supposed polychaete annelid Protonympha salicifolia, from the Upper Devonian (Frasnian) of New York State, USA, is redescribed. P. salicifolia has a bilateral and segmented body, but appears to have a ‘mattress-like’ construction with blade-like extensions along the margins. The affinities of P. salicifolia remain unresolved, but a proposed relationship to the annelids is unlikely. The preservation of the three known fossils, as mouldic imprints in sandstones, is strongly reminiscent of the circumstances associated with Ediacaran fossilization, and as such is an anomalous occurrence of such soft-part preservation in Phanerozoic sediments. Material associated with these enigmatic fossils has been referred to Palaeochaeta devonica, and also compared with the annelids. Such an assignment is also rejected. These fossils appear to be arthropodan, and are possibly myriapods. A supposed example of Protonympha (‘P’. marcellensis) from the Middle Devonian of New York State is now excluded from this genus, and it may be a crustacean.