The morphology of the genital operculum (a plate-like segment which contains the genital aperture) allows an easy differentiation between Bassipterus and the other adelophthalmids. The type A genital appendage (assumed to represent females) was long, reaching the second pair of abdominal plates, and was divided into three joints. The first had a short, triangular and hastate (with protruding lobes) portion followed by a tubular shaft that ended in two lateral triangular projections at the point of union with the following joint. The second joint was shorter and composed of three different areas. On both sides of the central shaft, two long narrow sclerites (hardened parts), possibly plates, lengthened themselves at their ends. The third joint was very short and finished in two long points reminiscent of Eurypterus, a more basal genus. The appendage in its entirety was covered by triangular mucrones which pointed outwards. The genital operculum differentiates Bassipterus from other eurypterid genera and suggests a close relationship with Pittsfordipterus.
