Vol I. 



Sun — Cambrian Faunas of North China 



(iv) 35 



impressed in the posterior part; the segments defined by the furrows are broader than the 

 furrows, strongly convex at the center and flattened at the margin. 



The border is practically a continuation of the slope of the segments and furrows 

 of the pleural lobes ; it is marked opposite the segments by short, backward-pointing flat, 

 broad spines not clearly defined, due to the strong weathering of the specimens, and 

 diagonally opposite the lateral angle of the axis by two long, strong, backward-extending 

 and little outward diverging thick and round spines. 



All the cranidia, and the associated free cheek are strongly marked by pustules 

 throughout. 



The associated pygidium referred to this species was also strongly pustulose, but 

 because of the weathered character of the surface, the pustules are only found in a few 

 places. The cranidium of this variety is rather similar to that of B. sinensis in form, but 

 it differs from the latter in its conical glabella, in the narrower fixed cheeks, in the strongly 

 pustulose character of the whole surface, in the narrow elevated frontal rim and in the 

 character of the pygidium. 



The main difference is that in the postero-lateral angle of the glabella the dorsal 

 furrows separate the fixed cheeks from the glabella whereas that of Blackwelderia sinensis 

 is replaced by a low ridge which connects the fixed cheeks and the glabella in the form 

 of a small triangular lobe. 



The associated pygidium of this species resembles more closely that of B. cilix; 

 but it differs entirely from the latter in the strongly pustulose character of .the surface, 

 number of axial rings, in the narrow rounded terminal ring and in having the long 

 spines close together at the margin and diverging outward instead of being parallt^l. 



This variety is characterized by its proportionally narrow fixed cheeks, strongly 

 pustulose character of the surface, well defined dorsal furrows, and the postero-lateral angle 

 of the glabella. 



Measurem ents : — 

 Cranidium 



Length of cranidium 



Width of cranidium at the palpebral lobe 



Width of fixed cheeks at palpebral lobe 



Length of Glabella 



Width of glabella at the base 



No. 5-23 a-b 



9.0 mm. 

 12.5 mm. 

 3.5 mm. 

 6.H mm. 

 6.0 mm. 



No. 524 



8.3 mm. 

 "10.0 mm. 

 3.0 mm. 

 6.0 mm. 

 5.2 mm. 



No. 525 



8.0 mm. 



10.5 mm. 



3.2 mm. 



6.0 mm. 



5.2 mm. 



