216 Mr. Salter on Palaozoic Fossils from South Africa. 



curious beak-like process in front, the body-joints in connexion with the tail, and 

 two or three varieties of the tail itself. From the size of fragments which occur 

 with the more perfect specimens, it must have been a very large Trilobite, — 

 probably more than a foot in length. The species is sufficiently distinct from 

 H. armatus, figured by Burmeister from the Devonian rocks of the Rhine ; it is 

 nevertheless very closely allied to it. 



The entire form was elongate, pointed at both ends, and broadest at the base of 

 the head ; tapering thence gradually backwards. The head, of which we have 

 good specimens, is convex ; the body is also very convex (the fine specimen, 

 fig. 4, has been rather flattened on the middle of the back), and the sides are 

 steeply bent down, so that the entire form was convex and subcylindrical. It was 

 ornamented with large scattered spines along the thorax, the base of the tail, and, 

 in some specimens, even on the head (see the large specimen, fig. 3). 



The head is subtriangular and but little rounded on the sides, broader than long 

 in the proportion of thirteen to eight, flattened out in front towards the beak, and 

 highly convex behind, so as to present a triangular outline in a side view (fig. 1&). 

 The cheeks are very convex, almost inflated, and bent down so steeply as to 

 appear, when seen from above, much narrower than the glabella ; — they are how- 

 ever about the same breadth, and have at their inner margin, close to the base of 

 the glabella, an oval flattened space* (fig. Ic). 



The glabella itself is urceolate, broadest below, contracted above, and blunt at 

 its well-defined front margin. The basal, middle, and upper lobes show themselves 

 distinctly. It is separated from the prominent neck-margin by a strong furrow, 

 and is bounded in front by the broad concave margin, beyond which the strong 

 curved apiculus projects from the thickened edge. This apiculus is the tuberclef 

 upon the hypostome or rostral shield, — the latter being conspicuous in this species 

 as a triangular large plate beneath the front margin (fig. 2). A similar, but much 

 smaller, tubercle is seen in the hypostome of Calymene and of Encrinurus. 



The facial sutures are very distinct, and there is a marginal suture along the 

 outer edge of the cheeks. The eyes are small, round, and prominent ; and are 

 placed on the middle of the very tumid cheeks, less than half-way up the head. 

 The cheeks are not distinctly margined, except posteriorly, where the strong 

 neck-furrow separates a thickened and often spinose margin (figs. 1 a & 16). 



The whole of the head is covered with a strong granulation, which is less con- 

 spicuous in the furrows, but is not absent from any part of the upper surface ; 



* A similar depressed oval space occurs at the same spot in Illanus Barriensis. See Memoirs Geol. 

 Surv. Decade 2. pi. 4. fig. 8a. 



f A double tubercle is seen on the hypostome of a species from the lowest Devonian of the Hartz 

 Mountains. It is the H. Schusteri of Romer, Palseontographica, vol. v. t. 3. 



