the fact that the known fragments of Pterygotus cobbi, from the same locality and formation, also represent a colossal animal, it is possible that the rami of P. cobbi and the telson of P. grandis will prove to belong to the same animal.
Pterygotus monroensis Sarle
Plate 70, figures 3–5
Pterygotus monroensis Sarle. N. Y. State Palaeontologist Rep't. 1902. p. 1102, pl. 24, fig. 7, 9
?Pterygotus sp. Sarle. Ibid. p. 1104, pl. 24, fig. 6, 8
Sarle describes this species as follows:
This species is founded on a single specimen, a cephalothoracic shield. The outline of this shield is semielliptic with the posterior edge noticeably incurved. The surface is moderately convex, and along the sides and front is a threadlike border. The length of the shield, without the genal angles, is 30 mm, with them 37 mm; the breadth at the base 38 mm. The compound eyes are prominent and project beyond the outline of the shield. They are subelliptic. with a distinct angulation on the inner side of each, produced by an indentation of the inner anterior part. They are 14.5 mm long and 6 mm wide. The facets can be made out with a good magnifying glass. The eyes are located a distance equal to their own length from the front of the shield and 27 mm from each other. A line connecting their bases cuts the axial line a little back of the center of the shield. The ocelli are on a small tumescence just back of this. The ornamentation is almost obliterated, but can be made out at one point, where it consists of minute, short, flat, lobelike scales.
Its differences from P. macrophthalmus are also indicated by the author as follows:
The cephalothorax of this new species differs from that of P. macrophthalmus in that its length is nearly equal to its breadth; the compound eyes are over one third the length of the shield, elongated, angulated on the inner side, situated farther back, and separated by nearly twice their length. In P. macrophthalmus the length of the shield is three fourths the breadth; the eyes are about one third the length of the shield, anterior, globular and separated by a distance about equal to their length.
The type specimen, which is in the State Museum, possesses some characters quite suggestive of a more proper reference to Hughmilleria. Sarle remarks that the form of the eyes suggests those of "P. bilobus
