edge; antelateral angles rounded; lateral margins divergent forward and gently convex; posterior margin slightly concave, the edge slightly raised; genal angles obtuse; lateral eyes large, about one third the length of the carapace, situated in the antelateral angles and submarginal, with semicircular eye nodes and crescent-shaped (when compressed) visual surfaces; ocelli situated between the posterior portions of the lateral eyes. No ornamentation has been observed.
Horizon and locality. Two specimens have been found in the Frankfort shale at Schenectady, N. Y.
Remarks. The carapace described here differs from the preceding species mainly in the posterior contraction. In this feature it agrees closely with D. otisius, a species from Otisville. The eyes in position and form are typically those of Dolichopterus.
The type specimen measures 14 mm in length, 14 mm in frontal width and 9 mm in basal width. The eyes are 4.5 mm long.
Dolichopterus otisius Clarke
Plate 46, figures 1–8
Pterygotus? otisius Clarke. N. Y. State Mus. Bul. 107. 1907. p. 308, pl. 6, fig. 6, 7
Description. The original description of this species is:
An elongate subquadrate head with eyes anterior, far apart and just within the margins; ocellar mound well back between the posterior horns of the eye crescent; surface quite smooth. The specimen figured and one other of similar character are all that is known of this species.
Although later collections have afforded us upward of 30 specimens of this odd species, none of them retains more than the carapace and two body segments. The generic determination is therefore dependent as before on the character of the carapace and suffers the resulting lack of positiveness. The better and varied preservation of the new material which ranges considerably in size, permits however a greater elaboration of the description.
