Pterygotus ? (Eusarcus) nasutus nov.
See text figures 102, 103
A number of carapaces from Catskill fail to show any distinguishing features from Pterygotus? (Eusarcus) nasutus (described on p. 382) from the Schenectady beds at Schenectady, and we therefore refer them to that species, although the considerable difference in 
Fig. 102, 103 Pterygotus ? (Eusarcus) nasutus nov. Two carapaces showing the characteristic angular front and the position of the eyes. Fig. 102 × 2; fig. 103 × 1.5 age between the forms makes it somewhat improbable that they are conspecific. The sculpture is well shown in several specimens and consists of flat closely arranged rather large nodes or tubercles, as in Eusarcus linguatus. A like sculpture is shown in some of the specimens from the Schenectady shale. In the first description the species is assigned to Pterygotus, but the closely related species from these Normanskill shales, Eusarcus linguatus, indicates that it may more likely be an Eusarcus.
Pterygotus normanskillensis nov.
See text figure 104
This name is proposed for carapaces of distinctly pterygotoid aspect.
Fig. 104 Pterygotus normanskillensis nov. Holotype. × 1.5. The parallel lines indicate the cleavage lines appearing in the carbonaceous film
Carapace broadly subrectangular, three fourths as long as wide; lateral margins subparallel, slightly convex, antelateral angle distinct, abruptly rounded; anterior margin broadly and evenly convex. Basal margin slightly concave in middle, postlateral angles approximately rectangular. Lateral eyes marginal, situated in the antelateral corners, elliptic, small, less than one fourth the length of the carapace. Surface sculpture not seen. Measurements of type specimen, length, 11 mm, width, 15 mm.
The presence of a genus of the Pterygotus group
