When I first found my first Calyptulax cephalon in the Verulam formation I had to ask my friend Kevin: "What the heck is a Phacops doing in the Ordovician?" He pointed out to me that the glabella on a Calyptulax doesn't look quite like the one on a Phacops but they do both share similar eyes.
Calyptulax is a somewhat common trilobite in the Verulam with it's cephalon being the easiest part to spot. The plate below has one as well as a pygidium from a Felxicalymene among other fossil debris.
Another plate holds at least three.
An angled view of of of the cephalons from the above plate/
Kevin has been very patient and put up with my many mispronunciations of Calyptulax (Calypsolax, Collapasox, Californiax, etc.). Calyptulax is a Phacopid trilobite and is related to Flexicalymene, Greenops, Dalmanites, Dipleura as well as Phacops for which the order is named.