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 | 27 | |
| Width of carapace | 30 | |
| Width of base | 22.5 | |
| Length of lateral eyes | 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 also seen in 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, indicating a powerful organ, but lack the distinct development of lobelike appendages seen in D. macrochirus and still more striking in D. stylonuroides.
