"eysyslopterus" is a little known eurypterid, with only one specimen collected that only preserves the prosoma ("head") with no appendages (limbs). the prosoma was rather broad, with a parabolic (approximately u-shaped) outline. it was 19.5 millimetres (0.77 in) long and 22 mm (0.87 in) wide. although the anterior part of the prosoma is not preserved, the fossil mold indicates a pointed portion. the posterior border was slightly convex. a narrow rim surrounded the lateral margins of the carapace (dorsal shield of the prosoma). the prosoma surface was gently arched, with the central portion rather level. the eyes were reniform (bean-shaped) and with a thin and light-colored test (external "shield") on its surface. they measured 4.5 mm (0.18 in) in length. the ocelli (simple eyes) were located in the posterior half of the prosoma and consisted of two circular spots. the posterior part was smooth, but the previous part had a distinctive ornamentation. this ornamentation extended until the end of the eyes and was composed of transverse lines developed as deep furrows.