Page:Pocock, The Scottish Silurian Scorpion.pdf/5

 as compared with those of existing forms. The second segments project on each side of the antero-lateral angles of the carapace, and are granularly sculptured. The anterior surface of the third segment is apparently normally crested above and below, and the fourth segment of the left side shows traces of the basal prominence so noticeable in living species. Granules are observable along the anterior side of both these segments. The fifth segment (hand) of the left side differs in shape from that of the right, being more oval in form, with its posterior border in approximately the same straight line as that of the distal segment, the bulge being confined to the anterior surface as in the Gotland specimen and recent species. On the right side the hand is unusually globular, its posterior surface, probably owing to crushing, being abnormally swollen. The fingers are thinner, more taper, and straighter than in the Gotland specimen and recent scorpions. No distinct joint between the finger and hand is discernible, although presumably it is the under side of the hand and of the moveable finger that is exposed to view, both on the right and left sides. It is possible that the shallow median longitudinal groove observable on the finger of the right chela represents the line along which the two fingers meet when closed. The finger of the opposite side is similarly marked with a fine sculptured ridge.

.—So far as can be ascertained the legs resemble those of the Gotland specimen in length, strength, and segmentation. As in other scorpions, and typically in all orders of Arachnida, they increase in length from before backwards, the fourth pair being nearly half as long again as the first. They consist, moreover, of what is doubtless the primitive number of segments—namely, seven. Primitiveness of segmentation is also shown by the subequality in length of the individual segments—a character which, in conjunction with the sharply pointed, practically clawless terminal segment, serves to distinguish the legs of  from those of all other scorpions, living or fossil. I say