The figure below shows the distribution of samples containing the trilobite Calliops.

[ Calliops distribution

Calliops is an uncommon trilobite in the MRV strata.

[ Calliops ]
Figure modified from Sloan, North American Ordovician Trilobites.

Calyptaulax (Calliops) Delo, 1935 [*Phacops callicephalus Hall, 1847]
Glabella with 1p lateral lobes detached; 2p lateral glabellar furrows narrower and shallower than 1p and 3p furrows but reaching axial furrows; eyes very large, close to glabella and posterior border furrows. Pygidium with 8 to 11 axial rings and 4 to 8 pairs of ribs, pleural furrows distinct, interpleural furrows distinct or obsolescent.
M. Ord. - U. Ord., North America
Family Pterygometopidae Reed, 1905
Exoskeleton highly vaulted (with some exceptions). Glabella with frontal lobe more or less hypertrophic, especially in transverse direction, 3p glabellar lobes slightly to strongly hypertrophic at cost of 2p (and even 1p) lobes, 1p lobes narrow, tending to become detached from central area; 2p lateral glabellar furrows slightly to very oblique in anteromesial direction; posterior sections of facial sutures may be in distinct genal sulcus; genal spines present or absent. Pygidium subequal to cephalon in size, without posterior spine.
M. Ord. - U. Ord.
Order Phacopida Salter, 1864

NOTE: The classification of trilobites has undergone several revisions since the 1959 publication of Volume O of the Treatise. The classification presented here only represents a starting point for the search for further information.

Treatise on Invertebrate Paleontology, O492.