66 SYSTEMATIC ARRANGEMENT 



triangular axis and thirteen narrow flat radiating ribs, six on each side of the odd central 

 one. Of these ribs the odd one only (left at the end) is straight ; the other six pair, the 

 symmetrical lateral ones, are somewhat curved in the shape of the letter S- 



Remarks. — 1. Wahlenberg, in the place already quoted, has figured a fragment which does not 

 belong to the genus Bronteus. The caudal shield also does not resemble accurately the one I have 

 described, for it has only nine short broad ledges, which, however, are so unsymmetrically ai-ranged 

 that they are of themselves sufficient to convince us that the drawing is erroneous. I do not ventiire 

 to decide whether Count v. Miinster's B. Neptuni (see remark on the last species) belongs to the present 

 form. 



2. The genus Lic/ias of Dalman [Palaad 53, iv, and 73. Entomostr. laciniahis. Wahl. /. c. 34. 

 8. Tab. II, Fig. 2. Brong. /. c. 35. 3. PI. Ill, Fig. 3. Schloth. Nachtr. ii, 36. 19. Milne Edw. 

 Or. iii, 344. 3), which appears to me most nearly allied to Bronteus, I am obliged to omit, because 

 the fi-agments that have come under my obsei-vation exhibit nothing to characterize it.* 



Division C. 



Trilobites havi/u/ a simple but very small eaudal shield, the ax-is of which is many-jointed, hut 

 vJiich is always shorter than the body. OleniDjE. 



The two genera, Paradoxides and 0/e/ius, belonging to this division have been hitherto 

 united by the authors, but are distinguished readily and safely by the caudal shield, which 

 in Paradoxides has no lateral enlargement at the base, while in Olenus, on the other hand, 

 it is enlarged at that region, and thus generally assumes a trilateral shape ; the former genus 

 has from sixteen to twenty, the latter fourteen body-rings. 



Genus 6. — Paradoxides, Brongniart (Olenus, Sect. I, Dalman). 



Cephalic shield lunate, with a thickened but not reflexed mai-gin ; the glabella 

 clavate or oval, moderately convex ; enlarged anteriorly, divided into four portions by 

 three curved sutures, of which the posterior is the margin of the articulation with the 

 body. The lower part of the head (PI. I, Fig. 7, Ent. bucephalus — Wahl, et auct.) has a 

 less prominent boss, analogous to the anterior division of the upper part, which diminishes 

 posteriorly, and is terminated by a convex reflexed margin, having at each side an oblique 

 transverse impression. 



The facial sutures are nearly parallel in their principal direction, commencing at the 

 anterior margin on a line with the eyes, turning towards the eye with an S-shaped 

 curvature, forming a slightly arched lid, and returning in a similar S-shaped curve towards 

 the posterior margin. 



Eyes oblong, lunate, depressed, corresponding with the second division of the glabella, 

 reaching towards the anterior part nearly to the centre of the first division, and towards 

 the posterior margin rather beyond the commencement of the second ; eyelid rather more 

 convex than the neighbouring part of the cheek. 



Cheek-shield narrower than half the width of the cephalic shield, having a curved 



* Portlock, Lovon, and Beyrich have since published descriptions which give a tolerably perfect 

 idea of this form. It appears from their accounts that Dalman's Ampyx ? pac/iyrhynchus, Green's 

 Paradoxides Bottom, Castelnau's Platinotus and Actinurus, Eichwald's whole genus Metopias, and 

 Portlock's Nuttainia Mbern'ira, all belong to one genus, which ought to retain its earliest name of 

 Lic/ias. Dr. BejTich has undertaken to describe the species. 



