Abstract
Morphologically similar proetide trilobite genera occur in highest Devonian or lowest Carboniferous and in Middle Devonian strata, but are absent from the intervening Upper Devonian. The similarities have been accounted for either by true phyletic relationship, or by homoeomorphy. Genera from four proetide lineages are discussed, and it is concluded that these underwent ‘pseudoextinction’ in the Upper Devonian, presumably surviving in refugia of limited spatial extent that have not been preserved in the geological record.