Trilobita

Ptychopyge Angelin, 1854

Selection of related publications
Balashova, E. A. 1964. Morphology, phylogeny and stratigraphic meaning of the early Ordovician Ptychopyginae of Baltic. Voprosy paleontologii , 3-56. Voprosy paleontologi, IV, pp. 3-56.
References based on distribution