NO. 5 CAMBRIAN TRILOBITES 345 



postero-lateral limbs and narrow fixed cheeks merge into each other 

 so as to form transversely subtriangular areas, with the narrow pal- 

 pebral lobes on their front outer margins. 



Glabella large, subquadrangular in outline, and separated from the 

 fixed cheeks by clearly defined dorsal furrows ; its sides are nearly 

 parallel or slightly diverging ; front broadly rounded, almost trans- 

 verse ; surface marked by five pairs of furrows, the posterior of 

 which extends obliquely across the posterior portion nearly to the 

 center and separates a small triangular lobe on each side ; the next 

 two anterior pairs of furrows are short and extend inward at right 

 angles to the side of the glabella ; the anterior pair is nearly opposite 

 the front end of the palpebral lobe ; the anterior furrows are short 

 and extend obliquely inward subparallel to the front margin of the 

 glabella. Occipital ring narrow at the sides, widening toward the 

 center, where it is marked by a sniall, sharp node a little back of the 

 transverse center. Free cheeks large and surmounted on the inner 

 side by a narrow eye-lobe. The facial sutures cut the posterior 

 margin a little within the genal angle and extend obliquely inward and 

 slightly forward to the base of the eye-lobes ; curving over and 

 around the eve-lobes, they extend forward and downward, cutting 

 the front margin on a line with the posterior base of the eye-lobe. 

 Number of thoracic segments unknown. Single specimens of the 

 segments show that the axial lobe was nearly as wide as the pleural 

 lobes, that it was moderately convex, and that a small node occurs 

 at the center of each segment near the posterior margin; also that 

 on the outer side of each segment a rounded transverse node is 

 outlined from the main body of the segment by a slightly obliqjie 

 transverse furrow ; pleural lobes nearly flat out to the geniculation, 

 where they curve gently downward ; each pleura has a furrow that 

 is broad at its inner end next to the axial lobe and gradually narrows 

 to the geniculation, where it terminates within the somewhat broadly 

 rounded, outer extremity ; in well-preserved specimens a rounded 

 ridge starts near the inner end of the pleural furrow and extends 

 outward one-fourth of the length of the furrow. 



The associated pygidia are semicircular, with the anterior margin 

 almost transverse in the compressed specimens. The axial lob^ is 

 large and quite distinctly marked ; it is divided by three transverse 

 furrows into three rings and a terminal section that ends posteriorly 

 just within the outer border ; a small node occurs near the posterior 

 margin at the center of each rifig ; five anchylosed segments are 



