VI.—The Classification of the Phacopidæ

Abstract

The family of Trilobites termed Phacopidæ has been defined by Beecher as follows:—“Glabella tumid, widest in front. Free cheeks continuous, united anteriorly. Suture extending from in front of the genal angles inward to the eyes, and thence forward around the glabella. Eyes generally large, always with distinct facets, schizochroal. Thorax of eleven segments with grooved pleura. Pygidium usually large and of many segments; limb ribbed; margin entire or dentate.”