OF THE SPECIES. 71 



swelling of the margin makes a fourth division. The facial suture terminates as in Olcnus, 

 and the terminating angle of the check-shield is elongated. 



The caudal shield is semicircular, straight at the anterior jjart, bounded by a curve at 

 the posterior part ; the axis consists of five to six rings, and a fold proceeds from it towards 

 the posterior margin, which there projects in a large spine. This is all that is known of the 

 animal. 



Locality.— k calcareous blackish-gray alumslate of Rusielökbacken, near Christiania. 



Remarks. — 1. According to Boeck {Gcea norw. \, No. 18), tliis species is not properly placed here, 

 but forms witli Ceraurus pleureocanthemus (Green, Mon. 84, f. 10; Bronn, Let. i, 117, Tab. IX, Fig. 

 12 ; Milne Edw. Cr. iii, 346) a distinct genus. It is very probable that this view is correct, but since 

 I have not myself had the opportunity of examining the two species, I must leave the decision to others. 

 No doubt, however, Ceraurus represents a form closely related to the Olenides. In Green's figure 

 eleven body-rings and a broad caudal shield are represented, the latter bearing a spine on one side 

 exactly hke that of O. forficula.* 



2. Murchison [Sil. Sys. vol. ii, p. (558, Plate XIV, Fig. 8) has described a large caudal shield, to 

 which he gives the name Paradoxides bimucrotiatus, and this in many respects seems to hold an inter- 

 mediate place between the caudal shield of the last and of the next succeeding species. It is straight 

 at the anterior part, nearly an inch in width, and fiu-nished with a three-jointed axis, over which there 

 projects forwards one of the articulation. A fold proceeds to the margin from each ring, and the three 

 folds, like the rings themselves, become smaller posteriorly, so that the free semichcular margin is 

 furnished with six rather bent processes.! 



3. O. scarabeeoides : Scuto capitis convexo, vertice non elevato sublobato ; scuto caudali utrinque 

 tridentato, axi biarticulata. 



i?p/._BROMEL, Jcf. lift. Uj}.s. 1729. 521. //. 3, and page 528. 6, c Fig. Wahl. iV. J- 



ups. viii, 41. 13, Tab. I, Fig. 2. Brongn. Cr. foss. 34. 3, Plate III, Fig. 5. 



ScHLOTH. Nac//f. ii, 25. 3. 36. 17. Dalm. Palcead. 57. 5. Emmr. Bissert. 47. 6. 



Milne Enw. C/-. iii, 344. \, Pelf iira scarab. Antltes scarabcBoides, GoiiD f. Lecju/i. 



und Br. Jahrb. 1843, p. 544. 

 Of this species I am only acquainted with some fragments of heads and perfect caudal 

 shields, and from these I must declare it to be a species with which I am too little con- 

 versant to judge M'ith certainty respecting its systematic position. The glabella resembles 

 that of the first described species of this genus, but is relatively shorter, broader, more 

 convex, and the indentations, which are similarly divided, are slighter. The existing part 

 of the cephalic shield beside it is deeply depressed, and thereby indicates a very great 

 convexity of the cheeks. I think I recognize a trace of the eyelid in the region of the first 

 anterior sutui-e ; a distinctly reflexed margin is visible at the posterior part ; but I have never 

 distinctly seen the anterior and lateral margin. The caudal shield has a short two-jointed 

 axis, and a margin of articulation before the first joint ; it is extended on both sides more 



* A new species of Ceraurus has been described by Portlock {Rep. 257, Plate I, Fig. 7) as C. 

 globiceps. 



t In his treatise ' Ueber einige Böhmische Trihbiten,' Dr. Beyrich has shown that this species of 

 Murchison's, together with Tril. Sternberyi, Boeck, constitute a new genus, for which he proposes the 

 name Chirurus. He describes four Bohemian species of this genus, and includes also in it Cuhjmene 

 Sternbergi, C. propinqua, and C. articidata of Münster [Beitr. z. Pet. iii, 37, Tab. V) ; C. speciosa, 

 Dalman (Pal. 74) ; C. ornala, Dalm. {Arsber. am nya Zool. Arbet. 134) ; Amphion gelasimsns, Portlock 

 [Rep. 289, Plate III, Fig. 4) ; and Arge.i p/aiwspino.vi.t, Portl. (/. c. 272, Plate Y, Fig. 9) ; the two latter 

 being probably the cephalic and caudal shields of the same species referable to this genus (Chinirm). 



