(iv) 72 Palxontologia Sinica Ser. B. 



^^Ptychaspis walcotti differs in both varieties from Pt. angulata characteristic 

 of a little older horizon from the Cambrian of the region of Yen-minh, by the more 

 clearly rectangular contour of the glabella and by its fainter convexity. The marginal 

 anterior rim, in Pt. walcofti is large and continuous to the glabella, Avhile a narrow limb 

 separates it in Pt. angulata. These notable differences are also noticeable between the 

 pygidia found with the fragments of heads of these two species. The pygidia associated 

 with the cranidia of Pt. angulata are bounded by a smooth limb all over their 

 circumferencial contour. The segments of pleural lobes are very apparent; it has been 

 noted that on the pygidia found with Pt. ivalcofti, they are almost entirely erased." 



One cranidium from Sha-Kuo-Tun probably belongs to the long variety of 

 the Tonking species. It has a broad occipital ring, a straight anterior edge of the 

 anterior lobe, moderately convex rectangular anterior lobe and large elliptical tubercles. 



In these respects, as well as in size, our specimen agrees fairly well with Mansuy's 

 species. This is the first example of this species found in China, although it occurs 

 abundantly in the Upper Cambrian of Tonking. This suggests that the Shakuotun 

 limestone of Fengtien is equivalent to the zone of Ptychaspis malcotti, the uppermost 

 zone of the Upper Cambrian of Tonking. 



Measurements : — 



Length of cranidium 9.5 mm. 



Length of glabella 6.5 mm. 



Antero-posterior width of anterior lobe 5.2 mm. 



Width of second lobe 1.5 mm. 



Width of occipital ring 2.0 mm. 



Width of frontal rim 1.2 mm. 



HoEizoN AND Locality: — Upper Cambrian: from Shakuotun limestone, 

 Sha-Kuo-Tun, Chin-Hsi-Hsien, Feng-Tien. Collected by Dr. J. G. Andersson. 



Ptychaspis subglobosa Grabau (Mss ) (sp. nov.) 

 Plate V, Figs. 3 a-d 



1923 Ptychaspis subglobosa (Grabau), Sun. Bulletin of the Geological Society of China Vol. 11 No. 1-2 



(listed) 



"This species is represented by four glabellas with parts of fixed cheeks attached 

 (one of the specimen is shown from the under side and two are very imperfect). 



