OYBBLE. 1:51 



this form the head-shield is nearly three times as wide as long, and of a broad, 

 semicircular shape. The glabella is short, convex, subcylindrical, expanding a 

 little in front, about three quarters as wide as long, slightly swollen in front, and 

 possessing three pairs of nodular lateral lobes, of which the anterior pair is the 

 largest and the basal the smallest. The frontal lobe appears to be transversely 

 rhomboidal, and has a pair of conspicuous tubercles in the middle. There is also 

 a single tubercle midway between the anterior pair of lateral lobes. A strong 

 occipital furrow marks off a convex neck-ring, furnished with a median tubercle. 

 The axial furrows are deep. The fixed cheeks are very wide, being from two to 

 three times the width of the glabella, and are gently convex, and bent down and 

 backwards towards the genal angles. The neck-segment is narrow, but Avidens 

 towards the genal angles, and is marked off from the cheeks by a strong furrow. 

 The genal angles are rounded. The posterior branch of the facial suture appears 

 to run nearly parallel with the hinder border of the head. The eyes are small, 

 elevated, and situated at the level of the anterior lateral lobes of the glabella, 

 lying at a distance from the glabella of more than half its width. A narrow, 

 rounded, ocular ridge connects them with the glabella. The cheeks are pitted, and 

 bear also four or five large remote tubercles. A few small tubercles are scattered 

 over the glabella. 



The pygidium, which may be associated with this type of head-shield on account 

 of its size, is sub-oval, with a conical axis tapering gradually to a bluntly pointed 

 extremity, but not reaching the posterior margin of the pygidium. The axis is 

 furnished with 2 — 3 complete rings at its anterior end, followed by about twelve 

 narrow rings incomplete in the middle, leaving a smooth central space down the 

 axis. The lateral lobes are formed by four pairs of simple, rounded, curved ribs 

 of equal size, ornamented with small tubercles and separated by rather deep furrows. 

 These ribs curve outwards and then backwards to run almost parallel with the axis, 

 and end behind it in short free points of sub-equal length. 

 Dimensions. — 



Width of head-shield .... 13"0 mm. 



Length of ,, (imperfect) . . + 4*5 ,, 



,, ,, glabella .... 4*5 ,, 



Width „ „ at base . . . oV „ 



Length „ pygidium .... 3"5 ,, 



Affinities. — The species which seem most nearly allied to this form are 

 ( '. kutorgse, Schmidt, 1 and C. brevicauda, Aug. 2 The head-shield also recalls that of 

 C. verrucosa, Dalm., but the state of preservation does not admit of a minute 

 comparison. 



1 Schmidt, ' Rev. Ostbalt. Silur. Trilob.,' pt. ii, p. 217, pi. xv, figs. 11—14. 



2 Augelin, 'Pal. Scand.,' p. 89, pi. xli, tig. 14; and Schmidt, op. cit., \>. 21!', pi. xiv, figs. 7—10; 

 pi. xv, figs. 15—17. 



