E. V. Bushuev, A. L. Makarova

This work is a continuation of the article «Middle Cambrian Agnostoid trilobites of the Chaya Formation from Ust-Mayskaya 366 well (south-east of the Siberian Platform)» by A.L. Makarova, E.V. Bushuev. This article presents the characteristic of the Middle Cambrian polymerid trilobites found in a small interval of the Chaya Formation (1313,55–1290,3 m) of Ust-Mayskaya 366 well. The 5 genera, 5 species (including aff.), 5 forms identified to genus and 3 forms in open nomenclature are described. The composition of the fossils indicates the Tomagnostus fissus – Paradoxides hicksi Lone and Anopolenus henrici Lone of Middle Cambrian Mayan Regional Stage.

Key words: polymerid trilobites, Middle Cambrian, Mayan Regional Stage, Ust-Mayskaya 366 well, Chaya Formation.