OP THE SPECIES. 69 



tlie exact number which seems to have been seen by Dahnan, whilst seventeen have been 

 given in his and Wahlcnberg's figure. Brongniart's very excellent figure exhibits also 

 sixteen, probably the correct number. The lateral lobes of the first body-rings are very 

 broad, broader than the axis, but they rapidly get smaller posteriorly, so that the last 

 become narrower than the axis. The caudal shield is small, roundish, transversely elliptical, 

 and has no lateral lobes. 



Local if J/. — The same as F. bohemicus and P. Tessini ; and also in the clayslate of Angers, 

 associated with Oyyc/ia Gunttardi. (Vide Guettard, Mem. de I' Acad des Sciences, torn, xiv, 

 ann. 1757, PI. VI, 8, Figs. 3. 4. 5.) 



Remarks. — Various species hitherto impci'fectly kuowu appear to belong to this genus. Among 

 these are — - 



1. A figure bv Count Razoumousky, in the Annales des Sciences (t. viii, PI. XXVIII, Fig. 11). 

 While possessing a similar structure with 0. bohemicus, this specimen is distinguished by a long spine 

 at the extremity of the caudal shield. Locality. — In Silurian strata between St. Petersburg and Lake 

 Ladoga. 



2. Paradox. Boltoni, Bigsby (Green, Mon. 60, f. 5, Joum. Ac. N. S. of Phil. vol. iv, p. 365, 

 PI. XXIII. Harlan, Zool. res. 303. Milne Edw. Crust, iii, 314, n. 1). This genus, as we have 

 already seen, belongs to the genus Lichas, Dalman. See Remark 2, under Bronteus laticauda. 



3. Cahjm. actinura (Dalman, K. V. Ac. Hand. 1824, 370, Tab. lA^ Figs. A, B, C. Hising. Leth. 

 suec. 11, Tab. I, Fig. 7. Milne Edw. Crust, iii, 321). A species having fifteen (?) lateral lobes and 

 body-rings, and resembling so closely in every respect P. Boltoni, that I cannot but refer them to the 

 same genus, intermediate between Bronteus and Paradoxides, the chai'acters of which canuot yet be 

 determined with certainty. 



4. Parad. Harlani (Green, Silliman's Am. J. of Sc. and Arts, vol. xxv, p. 336. Harlan and 

 Milne Edw. as before cited). 



5. All the other species hitherto iucludcd among Paradoxides or Olcnits, probably belong to the 

 following genus. 



Gcii/fs 7. — Olenus (Paradoxides p/Olenus Aucfonim). 



Cephalic shield constructed as in Paradomdes, but comparatively bi'oader and shorter ; 

 the glabella parabolic, not broader towards the anterior part, but rather more narrow and 

 rounded, at each side furnished with three slight furrows, which separate it into four 

 divisions, of which the posterior narrow one is articulated with the body. 



Eyes oblong curved. The facial suture originates at the anterior margin, in the region of 

 the eye. It is there bent at an angle, and returns nearly parallel to its former direction 

 towards the eye, where it makes a bent plate, and passes in an S-shaped curve towards the 

 posterior margin, where the two sutures gradually and continually diverge. 



Cheek-shield tolerably broad, with a reflexed margin, and with a pointed but not very 

 long posterior angle. 



Axis of the body many-jointed (fourteen ?) ; the joints more narrow tlian the lateral 

 lobes, short, and moderately convex; the lateral lobes extended in a straight line, only 

 terminating at the end in a short point directed backwards ; each furnished with a diagonal 

 furrow from the anterior and internal towards the posterior and external part. 



Caudal shield much broader than long, semicircular, straight at the anterior part, 

 arched or obtusely angular, trilateral posteriorly, with a distinct articulated axis. 



Localifi/. — In very old strata with species of the preceding genus. 



