Dalmannia

Dalmannia, a genus of Trilobites belonging to the family Phacopidae, found in the Silurian and Devonian systems. The best known English species is Dalmannia longicaudata, from the Upper Silurian. The genus differs from Phacops - the type of the family - by its pointed "free cheeks" (the hinder outer angles of the head) and the sharp tail-like spine on the "pygidium," the hindmost division of the body.