Pterygotus (Eusarcus?) nasutus nov.
Plate 86, figures 6–10
Description. Carapace pentagonal; one fourth wider than long, consisting of a greater posterior quadrilateral portion and a smaller triangular frontal portion; the lateral eyes occupying the anterior angles of the quadrilateral portion. The lateral margins are subparallel, gently convex, the frontal margin transverse for a short distance and bluntly angular in the middle; the posterior margin nearly straight transverse. The lateral eyes, about one third the length of the carapace, appear broadly triangular when partly folded under the carapace and compressed, but are normally subcircular and strongly project in the middle. Ocelli forward of center of carapace. Ornamentation small, crescent-shaped scales.
Horizon and localities. Frankfort shale (Schenectady facies) at Schenectady, Aqueduct and Duanesburg.
Remarks. This species is well characterized by the snoutlike frontal projection and the prominent antelateral angles with their large eyes. It does not appear to have reached the dimensions of the preceding species, the largest carapace being only 30 mm wide and 22 mm long. The type specimen is 9.5 mm long and 13 mm wide. Its lateral eyes are about 4.5 mm long.
Pterygotus prolificus nov.
Plate 86, figures 1–5
Description. Carapace semielliptic to roundish quadratic; length to width approximately as 4 : 5; frontal and lateral margins evenly convex, posterior margin straight transverse to gently concave. Lateral eyes large, one third the length of the carapace, elliptic in outline, marginal, situated in the antelateral corners, showing traces of facets. Ocelli subcentral in position. Ornamentation not observed.
Horizon and localities. Frankfort shale (Schenectady facies) at Schenectady, Aqueduct, Rotterdam Junction, Duanesburg, Schoharie Junction and the Vly creek. This is the most common eurypterid of the Frankfort shale; it is, however, possible that more than one species is comprised in this preliminary description.
