﻿136 BRITISH FOSSIL CRUSTACEA. 



form an angle wherein appears a central tubercle; also by the small, acutely angular 

 protuberances, like spines, which are diffused over the surface of the head beneath the 

 eyes. The characters of the feet cannot be given, as no vestiges of them, except very 

 slight ones, have turned up. In truth, there is no known species with which it can be 

 confounded, nor any approaching it in size." 



Of the other specimens of E. Scouleri from Mr. Powrie's collection, the head (PI. 

 XXV) is principally important on account of its under side (PL XXV, fig. \c, and 

 Woodcut, Pig. 41), which, after careful and patient development, has revealed the bases of 

 the great swimming-feet or maxillipeds {e, e), and a large elliptical plate (t, t), which I 

 can only interpret as the thoracic plate forced in and displaced by pressure, so as to 

 occupy its present position under the carapace. A second and inner plate, marked t ' , 

 underlies this opercular plate ; there are also remains of two pairs of endognathary palpi 

 (1 and 2) on either side. This assumed thoracic plate (?) is strongly arched, and is 

 divided down the centre by a suture (m), extending nearly to its upper and anterior border. 



A portion of one of the ectognaths is preserved upon the under side of the fine head 

 from the Andersonian University collection 1 (PI. XXVII) already described, but not in a 

 sufficiently perfect state to be worth figuring here. 



Body -segments. — We have evidence of ten body-segments belonging to this species, 

 two of which, the most anterior, are attached to the large head figured on PI. XXVII ; the 

 remaining eight are the most posterior of the body-rings, and are from Mr. James 

 Powrie's collection. 



These last named (PI. XXVI) being united in series, give a very excellent idea of 

 the peculiar short robust form of the body in E. Scouleri as compared with the other 

 species of Eurypteridce. The segments are very short in proportion to their breadth 

 and thickness, and are folded in along each margin, so as to form a most powerful series of 

 articular surfaces to the body-rings, capable of offering enormous resistance to external force. 



The subjoined Woodcut (Pig. 42) may serve to illustrate this structure, which presents 

 a stronger form of body-joint than that of any modem Crustacean with which I am 

 acquainted, there being no interspace between the body-rings protected by connecting 

 membrane, as in many Macrouran Decapods, but the solid somites are each furnished 

 with a broad infolded margin (measuring, in the second segment from the head, three 

 fourths of an inch in width), which is convex along the anterior border of each ring and 

 concave along the posterior edge, while the lateral angles are compressed into a ball in 

 front, and enlarged into a socket behind, so as to complete the powerful hinge of this 

 armour-plated body-covering. 



1 It is possible that some further light might be afforded as to the appendages of this very remarkable 

 species, by attempting to develope the underside of this last-named specimen, but the tough and concre- 

 tionary nature of the matrix, which yields most unwillingly under the chisel-point, renders the task of 

 removing it not only very difficult, but also somewhat dangerous to the specimen itself, which would be very 

 apt to shatter from the repeated blows required. I have therefore thought it more prudent to desist. 



