Rare Pliomera fisheri Russian trilobite

Coming from the Lower Ordovician Wolhovian Level deposits of the Wolchow River region near Saint Petersburg, Russia, this is an example of the rare trilobite Pliomera fisheri. It is a member of the Order Phacopida, Suborder Cheirurina. The trilobite itself is 2.3 inches long (measured along the curve) and 1.1 inches wide at the widest extent of the cephalon. Its caramel-colored Calcite shell is well set off by the white limestone matrix. The most distinctive feature of this trilobite is the notched pygidium. These trilobites are nearly always found in an enrolled condition with the pygidium neatly tucked under the cephalon. Enrollment was a defensive posture assumed by most trilobites. This one took it one step further; the notches allowed the trilobite to breathe freely while enrolled, allowing it to wait out any would-be predator. As always, the skillful Russian preparators have shown this fine specimen to best advantage, well-centered on its 3.0 inch by 4.0 inch matrix.