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The Ordovician Trilobite Hadrohybus Raymond 1925, And Its Family Relationships, R. A. Fortey

Postilla

The type species of the trilobite Hadrohybus Raymond 1925, H. dunbari from the Cow Head Group of western Newfoundland, is redescribed here. It has been regarded as a cheirurid, but analysis of its cranidial characters show that it is a bathyurid closely related to the well-known Early Ordovician genus Bolbocephalus, and it is considered to be a subgenus of that form. It is probably of early Middle Ordovician age. A second Hadrohybus species occurs in the late Early Ordovician of Vermont.