NO. 4 CAMBRIAN FAUNAS OF CHINA 89 



and merge into the arched palpebral lobes ; in front of the palpebral 

 ridge the cheeks descend rapidly and merge into the frontal limb ; 

 the postero-lateral limb is long and almost entirely made up of the 

 rounded, narrow posterior rim, strong intermarginal furrow, and a 

 narrow area between the furrow and the facial suture. Palpebral 

 lobe of medium length ; in a cephalon 18 mm. in length it has a 

 length of 4 mm. ; it is narrow and raised a little above the surface of 

 the fixed cheeks. Frontal limb broad and strongly concave in large 

 cephalons, becoming less so in smaller ; in front of the glabella it 

 slopes rather rapidly downward and then upward with a gentle curve 

 to the thin, rounded edge. Free cheeks gently convex, but become 

 slightly concave toward the outer margin in the larger specimens. 

 The genal angles are extended into short spines. 



Thorax with eleven nearly transverse segments ; axial lobe convex 

 and a little more than one-half the width of the pleural lobes. It is 

 strongly defined by a sharp angle where the segments pass into the 

 pleural lobes. Each segment arches forward slightly at the center, 

 also at the sides just before joining the pleural portion of the seg- 

 ment ; the pleural lobe of each segment is transverse for about one- 

 half its length, and then it curves gently down toward the falcate 

 termination. The pleural grooves start just within the front rim of 

 each segment next to the axial lobe, and, widening, continue with a 

 nearl}- uniform width for about two-thirds of the distance outward, 

 and then narrow, disappearing some little distance within the termina- 

 tion of the segment. 



Pygidium large, moderately convex, with a narrow, strongly con- 

 vex axial lobe and broad, slightly flattened margin ; axial lobe five- 

 sixths of the length of the pygidium, convex and narrowing gradually 

 from the anterior margin to its termination ; it is crossed by from 

 five to six shallow, transverse furrows that outline from six to seven 

 slightly convex rings and a terminal section ; from the axial lobe the 

 surface of the pleural lobes slopes at first gently and then quite 

 rapidly down for about two-thirds of their width and then very 

 gradually out to the margin. They are marked by five or six broad 

 furrows and rather broad, flattened ridges that are the continuation 

 on the pleural lobe of the transverse rings on the axial lobe ; the 

 posterior margin curves more or less inward toward the median line 

 so as to give a more or less indented outline to the otherwise rounded 

 curve of the sides and posterior margin of the pygidium. 



Surface under a strong lens shows numerous pits or pores ; the 

 free cheeks and the cranidium in front of the glabella and palpebral 



