270 NEW YORK STATE MUSEUM 
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 semt- 
circular 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 Frank- 
fort 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 g 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. 
