﻿Vol. 66.] THE CAMBRIAN ROCKS OP COMLEr. 43 



Fixed cheeks. — About equal in width to the glabella; nearly 

 flat for half their width, but curving steeply down to a wide furrow, 

 from which the surface rises again to the prominent eye-lobe. 



Eye -lobe. — Moderate in size (about half as long again as a 

 glabellar lobe) ; situated opposite the posterior pair of glabellar 

 furrows ; almost reaching to the posterior border. 



Ocular ri dge. — Commencing by a somewhat prominent rounded 

 boss (almost a tubercle) situated close to the axial furrow and a 

 little forward of the anterior glabellar lobe ; curving outwards and 

 backwards, the ridge rapidly loses prominence, and is only just 

 traceable across the forward swelling of the cheek to the eye-lobe. 



Postero-lateral limb. — Rather narrow; consisting of a wide 

 furrow and a somewhat sinuous raised rim, geniculated at about 

 three-quarters of the way out ; bending down steeply to the facial 

 suture. 



Frontal limb. — Distinct from the glabella, but continuous 

 with the cheeks ; falling away with a gentle convex curvature to the 

 marginal rim ; bent down decidedly towards the sides ; faint indi- 

 cations of radiate markings on the internal cast. The marginal rim 

 is somewhat convex, but not recurved, and of uniform width from 

 suture to suture. 



Facial suture [524] (PI. VII, fig. 5). — Anterior branch short 

 and direct from the eye-lobe to the depressed border ; posterior 

 branch curving outwards and backwards to cut the posterior margin 

 behind the eye-lobe. 



Test. — Covered with closely set tubercles, which are larger on 

 the elevated parts and sometimes hardly discernible in the hollows 

 of the shield. Qn the glabella they are speci ally large, and more or 

 less confluent. On the interior the tubercles are represented by 

 little pits, which on the internal cast show as tubercles rather 

 smaller in size than on the exterior. On the marginal rim the 

 tubercles are replaced by elongated narrow ridges, arranged in a 

 reticulate manner (PI. VII, fig. 6 b). 



Two detached free cheeks [438, 549] have been found intimately 

 associated with the fragments of these cranidia. One of these has- 

 a portion of the test preserved, which shows characters similar to 

 those above described. Both specimens also resemble the head- 

 shields in the special method of preservation of the test, and I have 

 no hesitation in assigning them to this species. 



Free Chekk. — Xarrow and small, with a deep pit behind the 

 eye ; the genal angle is extended backwards into a strong spine of 

 circular section and of great comparative length. 



Thorax and PrciDirM unknown. 



A few thoracic segments are preserved in the same rock, but are 

 not sufficiently good to warrant description. 



Locality and horizon. — Comley ; from the uppermost band 

 of the grey limestone at the excavation, 200 yards south of the 

 quarrv. 



