A double-spired athyridoid, morphologically transitional between Early Devonian Helenathyris and Late Devonian Biernatella has been identified in the Givetian of the Holy Cross Mts., Poland. It appears that in the course of evolution between these brachiopods dental plates and cardinal plate atrophied. The biernatellids may have developed a diplospiralium independently of Triassic diplospirellids. They originated either from the Siluro-Devonian lineage represented by Coelospira, Anoplotheca, Bifidia and Kayseria or, more likely, they can be derived from their pre-Devonian common ancestors. Biernatellids were probably well adapted to environments with a poor supply of food. Eobiernotella rackii gen. et sp. n., Biernatella ovalis sp. n., and B. lentiforrnis sp. n. are proposed.

Key words: athyridoid brachiopods, diplospiralium, phylogenetic relationship, Devonian.