The Peronopsidae (which may also be called peronopsids) comprise the earliest family of the Agnostina suborder.

[2] Some scholars do not consider the Agnostina true trilobites, and consequently rejected the idea that they were related to the Eodiscina.

[3][4] Many lineages are thought to have evolved within the Peronopsidae, six of which gave rise to later Agnostina families.

Like all Agnostida, members of the Peronopsidae are diminutive, with the headshield (or cephalon) and tailshield (or pygidium) of approximately the same size (or isopygous) and outline.

The preglabellar furrow - between the front and the central raised area of the cephalon (or glabella) - is lacking or incomplete.