The general form of the body (Fig. 161) is somewhat like that of a Scorpion, but is relatively broader and shorter. On the surface of many parts of the exoskeleton numerous scale-like markings are found (Figs. 162, 163).[231] The =prosoma= or cephalothorax consists of six fused segments covered by a quadrate carapace with its front angles rounded. This bears on its dorsal surface two pairs of eyes—large kidney-shaped lateral eyes and median ocelli (Fig. 161, _b_, _a_). The margin of the dorsal part of the carapace is bent underneath to form a rim which joins the ventral part of the carapace. On the ventral surface of the prosoma (Fig. 162) six pairs of appendages are seen, of which only the first pair (the chelicerae) are in front of the mouth. The chelicerae are small, and each consists of a basal joint and a chela, the latter being found parallel to the axis of the body; they closely resemble the chelicerae of _Limulus_. The remaining five pairs of appendages are found at the sides of the elongate mouth, and in all these the gnathobases of the coxae are provided with teeth at their inner margins and were able to function in mastication, whilst the distal part of each appendage served as an organ of locomotion. The posterior part of each coxa is plate-like and is covered (except in the case of the sixth appendage) by the coxa of the next appendage behind. A small process or “epicoxite” is found at the posterior end of the toothed part of the coxae of the second, third, fourth, and fifth pairs of appendages. The second appendage consists of seven joints, whilst the remaining four consist of eight joints; none of these appendages end in chelae. The second, third,[232] and fourth pairs of appendages are similar to one another in structure, but become successively larger from before backwards. These three pairs are directed radially outwards; each consists of short joints tapering to the end of the limb, and bearing spines at the sides and on the under surface, and also a spine at the end of the last joint. [Illustration: FIG. 162.—_Eurypterus fischeri_, Eichw. Upper Silurian, Rootziküll, Oesel. Restoration of ventral surface; 1–6, appendages of prosoma; _m_, metastoma. Immediately posterior to the metastoma is the “median process” of the genital operculum. (After Holm.) ] The fifth appendage is longer than the fourth and is directed backwards; its second and third joints are short and ring-like; the others (fourth to eighth) are long and similar to one another, each being of uniform width throughout; the last joint is produced into a spine on each side, and between these two is the movable end-spine; the other joints do not bear long spines as is the case in the three preceding pairs of appendages.