Her eis a rare Trilobite from England of the species Dindymene didymograpti
The Genus Dindymene belongs to the famlay of Encrinuridae and is quite widely distributed in the Ordovician. However it never  occurs in larger quantity’s.
This trilobite  specimen offers a very fine and detailed preservation, espesaly the head is very nice preserved. The pygidium seems to be primary lost or been flipped under thorax.

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