This is a good split, although part of the shell on the right side of the head got left on the counterpart, which I also have. The axial nodes are well preserved. As a black trilobite on a black rock this doesn't make my most displayable trilobite.

Is this a distinct species from Triarthrus eatoni? According to paleontologists John L. Cisne. Joane Molenock, and Bruce D. Rabe, the answer is "no". In Evolution in a cline: the trilobite Triarthrus along an Ordovician depth gradient they write: Head proportions in the trilobite Triarthrus change by small but significant amounts with both lime and environment along a ‘fossil’ depth gradient in the Trenton Group of central New York. The putative zone species T. becki (Denmarkian Stage) and T. eatoni (post-Denmarkian; =T. becki, new synonymy) intermingle throughout the roughly two million year long sequence studied. The two represent extreme morphs in a graded spatio-temporal cline, not distinct species.

So you may want to see this page as merely giving the conventional carapace only view of Triarthrus eatoni, showing the axial nodes very nicely.