The central raised area (or glabella) of the headshield (or cephalon) is moderately to strongly inflated near to its front, more or less flattened on the top, falling vertically to or slightly overhanging the border furrow.

In the ventral surface of the seam (or doublure) is in the frontal half of the cephalon a continuous furrow, delineated by ridges, and with notches laterally.

Because similar spots in a specimen of Greenops boothi from the same site are arranged in rows, it may be assumed that they are original and not caused by the fossilisation process.

Eldredgeops has a raised ridge along the ventral margin of the cephalon, the glabella is more inflated, the lateral parts of the preoccipital ring are not round but rectangular, the palpebral area and palpebral lobe are larger than in P. latifrons, and there is no fold right behind the posterior vertical row of lenses, nor an isolated raised area just below the lenses.

[8] During the Eifelian in the present-day Belgian Ardennes, several Phacops species developed from each other, the oldest being P. imitator, followed by P. fragosus, then P. latifrons and finally P. sartenaeri.

[9] Fossils of Phacops salteri have been found in the trilobite-rich Late Emsian to Early Givetian Floresta Formation of the Altiplano Cundiboyacense, Colombia.