Illaenus

Illaenus is a genus of trilobites from Russia and Morocco, from the middle Ordovician.

Species included in this genus can reach a length of about 57 millimetres (2.2 in). They are without glabella and without articulation of the tail. The cephalon has a high profile and recurved genal spines. Eyes are distant from the axis of the head, situated nearer to the edge.