Bellacartwrightia is a relatively uncommon genus of Phacopid trilobite

Trilobite

Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...

, found in the mid-Devonian

Devonian

The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...

 Hamilton Group of New York state, mainly in strata exposed near Lake Erie

Lake Erie

Lake Erie is the fourth largest lake of the five Great Lakes in North America, and the tenth largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. It is bounded on the north by the...

 just west of Buffalo

Buffalo, New York

Buffalo is the second most populous city in the state of New York, after New York City. Located in Western New York on the eastern shores of Lake Erie and at the head of the Niagara River across from Fort Erie, Ontario, Buffalo is the seat of Erie County and the principal city of the...

. This trilobite is usually about 1.5" to 2" long. It was previously known as Metacanthina.
A very similar trilobite from the Devonian of Morocco is still sold as Metacanthina, but considerable research is still being done on Moroccan trilobites.