The main reason to collect in the black shales of the Collingswood member of the Whitby formation is in the hopes of finding an articulated Pseudogygites latimarginatus. Most of the time the only parts found are the isolated pygidiums. I have been fortunate enough to find one mostly intact example.
Specimen #1 - The large slab with a partially disarticulated example
Closer view of the specimen
This the the counterpart on a smaller flake of shale
Specimen #2 - An isolated pygidium
Specimen #3 - another pygidium
The Whitby formation is Ordovician in age (late Ordovician, Katian/Mohawkian stage).
fossils were collected from the St. Mary's Limestone Quarry in
Bowmanville, Ontario. I used William Hessin's book "South Central
Ontario Fossils", 2009, Self Published, pg. 200 to help identify these