Page:The Eurypterida of New York Volume 1.pdf/329

 joint seven, as restored to its natural position, would be 12.5 centimeters, exclusive of the basal joint at a a. The long spines of the joints 3 and 4 are 5 centimeters in length.

The joint marked (1) is broad and short with a rounded depression at the center of its inner margin. There is no evidence of the attachment of the long spines that are articulated to the posterior side of the succeeding joints. From the form of the joint and the presence of broken fragments of the test in the matrix at a a it is probable that it is the second joint of the appendage and that the first or basal joint is broken up. The joint (2) is large, elongate, rudely subtriangular, the long anterior margin curving around to meet the nearly straight posterior margin at its inner end. The latter margin has nine long curved spines articulated to it while the three following joints (3, 4 and 5) have but three each on their posterior margins. These joints (3, 4, 5), are more or less quadrangular in outline, (3) and (4) being transverse and (5) a little elongate. The spines of (3) and (4) are the longest of any attached to the appendage. Beyond (5) traces of another joint are shown (6), and another is indicated by the position of the three curved spines beyond those of (6). These two latter joints were crushed by the forcing back of the long terminal joint (7), the inner end of which is seen beneath the center of the joint (4). This joint or terminal spine is slender, slightly curved backward, and marked by a slight median ridge and longitudinal striae. The surface of the joint (1) and the anterior portions of (2) and (3) show the scalelike markings observed on the fragment of the thoracic segment. If there were but one joint beyond the transverse joint (1), i. e., the basal, the entire appendage would have had nine joints, if our interpretation of the crushed joints is correct.

The long curved spines (s, s, s), are a very curious feature of the appendage and the most marked character of the genus and species. They are articulated to the posterior margin of the joints, as the latter rest flattened out in the slate or shale, and there is no evidence but that they form a single series as shown in the specimen and in the drawing, figure 2. Each spine is constricted a little near its base, forming a rounded end or point of articulation; from this well out toward their pointed termination they retain an average width curving gently backward and inward. They appear to have been flattened when in a natural condition, and formed of a thin test which is rather strongly striated.

Horizon and locality. Utica slate, Holland Patent, Oneida co., N. Y.

Remarks. The great width of the earlier joints of the leg and the very rapid tapering of the limb suggest that it was a first endognathite and that it consisted of eight segments, counting the terminal spine. It is