This specimen is from a now in accessible location. The new property owners aren't giving collectors access.
Trimerus dephinocephalus 7.5". Classic preservation with complete exoskeleton intact. As a point of interest. These monster trilobites from the Rochester Shale are more rare that Arctinurus boltoni. This specimen was found just west of Rochester, New York. It is the same horizon and the quarry but about 45 miles east of the quarry. The last one of these species was sold for about $2,000 and was about 1 1/4" smaller.