Exquisitely preserved trilobites from the Devonian of Morocco have been sought after by collectors, but their taxonomy has never been formalized and their field occurrence never documented. This monograph includes twenty-three species level descriptions of this famous fauna from Jbel Gara el Zguilma. Trilobites are preserved in storm deposits. Calcareous nodule formation during early diagenesis protected the trilobite fossils from compaction. Very careful preparation of the fossil material exposes many spectacular spiny forms including examples that deviate from bilateral symmetry that are apparently unique in the Trilobita.