Sometimes all you find is a fragment of a Trilobite, like the partial Amphilichas cephalon I detailed a couple of weeks back. Such is the case with the single, isolated cephalon below.
After reviewing the book "South-Central Ontario Fossils" by William Hessin, my first thought is that it came from a Bufoceraurus.
I posed the question to my friend Kevin who responded: "Your "Bufoceraurus" may be correct, but I think it may more likely be Ceraurus matranseris. There's a close up pic in Bill's book (pg 185) so you can compare for yourself. I base that choice on not seeing any tubercules on the first axial ring."
I need to examine the specimen more before I make a decision as to what name is correct and in order to do that I need to get it cleaned up a little more. I'll post an update in the future once the work is complete.