The osteology of the suspensorial and opercular series in representatives of 48 genera and 41 families of eurypterygian fishes were studied. The suspensorium consists of the palatine, ectopterygoid, endopterygoid, metapterygoid, quadrate, symplectic, and hyomandibular bones. The hyomandibular foramen is present at the base of the anterior head. The opercular series consists of the preopercle, subopercle, interopercle, and opercle. In most Eurypterygii, the preopercle is L-shaped and bears an open or closed preoperculomandibular canal.
