222 
PALEONTOLOGY OF NEW YORK. 
tapering rapidly, and was undoubtedly divided into several joints although the 
articulating surfaces cannot be detected. Along the lower margin of the 
appendage is a double series of strong spinous processes, each having a length 
of about 25 mm. Four of these and the bases of two others constitute the 
outer row, and portions of two members of the lower row are partially ex¬ 
posed. The terminal spine is incurved toward the tip, and all are characterized 
by the longitudinal elevated lines upon their surface. A fragment of the basal 
joint of the left leg of the same pair lies in its normal position, and a small 
portion of its mandibular process is exposed. 
The carapace has been so forcibly compressed upon the basal joints of both 
these appendages as to produce conspicuous ridges upon the surface equidistant 
from the anterior prolongation of the median ridge of the cephalon. 
Directly behind the base of the right member of this pair lies a single joint 
terminating in a chela, the whole measuring 60 mm. in length. The other 
joints of this appendage do not appear on the specimen, and it is impossible to 
determine positively whether this is, as it seems, the terminal portion of a third 
gnathopod, or is analogous to the chelate antennules of Limulus. 
A portion of a very strong basal joint, belonging to the left member of the 
third pair of appendages, has a diameter of 30 mm., a length of 35 mm., and 
bears a double lamellate mandibular extension, which is sharply serrate along 
its oral edge. This joint is followed by a small portion of a fourth gnathopod, 
which has a diameter of 40 mm., and though quite imperfect represents a very 
large appendage. Behind this, and lying in its normal position is the basal joint 
of the last or fifth pair of appendages. This is very broad and flat, as in other 
members of the EurypteridcB, has a length of 90 mm,, a width of 60 mm., and 
a thickness of 20 mm. at its distal extremity. The oral margin of the joint 
bears a row of conspicuous denticulations. 
According to the restoration of Stylonurus Logani given by Woodward (Mon. 
Brit. Foss. Merostomata, pt. iv, p. 131), the last two pairs of gnathopods were 
produced to a length nearly equaling that of the entire body. This may be 
true also of Stylonurus excelsior, and as the specimen under consideration bears 
the largest carapace of Stylonurus at present known to us, these appendages 
may have reached a length of upward of four feet. 
The evidence from this specimen confirms in most particulars Woodward’s 
restoration of the oral surface of Stylonurus, though there is reason to believe 
that the peculiar antennae there ascribed to the animal represent the first pair 
of gnathopods, and that there were five instead of four pairs of these append¬ 
ages as given by the author. 
