THE EURYPTERIDA OF NEW YORK 275 
surface of the carapace appears to have been uniformly convex, but just 
behind the frontal angle a rather sharp transverse ridge is observed. 
As in the other species of Dolichopterus, the compound or lateral 
eyes are situated within the margin where the frontal and lateral margins 
unite. They are of great size (one fourth the length of the head shield) and 
separated by a distance equal to their own length. The ocular node is 
semicircular in outline; the inner margin straight, the outer a semicircle; 
its top flat or slightly depressed; the visual surface is crescent-shaped. 
The ocellar node is situated between the lateral eyes; ocelli not seen. 
Measurements millimeters 
Length of carapace... 0... ce cece eee eee eee tenes 27 
Width of carapace... 6... eee eee ete nee 30 
Width of base... . cece ee ee et ene n nee 22.5 
Length of lateral eyes....... 0... eee eee ee eee Leas 7 
Horizon and locality. Bertie waterlime; Schooley’s farm, east of 
Crane’s Corners, town of Litchfield, Herkimer co., N. Y. 
Remarks. This species, as represented by the single carapace, is 
quite similar to D. otisius [comp. pl. 46, fig. 2]. It differs from 
the latter mainly by the greater extension of the frontal portion and by 
the more pronounced posterior contraction of the carapace. The frontal 
transverse ridge or fold observed in the species is alsoseenin D. otisius. 
The same locality has also furnished a swimming leg [pl. 57, fig. 1] 
which while distinctly belonging to a Dolichopterus, is greatly different 
from that of D. macrochirus, the only fully known congener 
occurring at Litchfield. We consider it therefore probable that it belongs 
to D. testudineus. Its most striking character is the development 
of the palette or ninth segment, which is very elongate elliptic, with an 
obliquely truncate base and which much resembles the palette (or eighth 
segment) of Pterygotus. The preceding segments are very broad, indicat- 
ing a powerful organ, but lack the distinct development of lobelike 
appendages seen in D. macrochirus and still more striking in 
 D. stylonuroides. 
