(iv) 36 



Palssontologia Sinica 



Ser. B. 



Width of occipital ring 

 Width of frontal rim 

 Pygidium (associated) 

 Length 

 Width 



1.5 mm. 

 1.0 mm. 



1.0 mm. 

 0.8 mm. 



1.0 mm. 

 0.8 mm. 



6.2 mm. 

 1 1.0 mm. 



Horizon and Locality: — Late Middle Cambrian: from thin-bedded limestone in 

 Kushan shale of Lin-Cheng, collected by Y. T. Chao and C. C. Tien. 



BlACKWELDERIA TIENI Sun (sp. nov.) 

 Plate II, Figs. 7 a-c. 



cfr. 1905 Olcnoidcs (?) cilix Walcott, Proc. U. S-^'at- Mus., Vol. XXIX, p. '27, (described and dis- 



cii^seil a8 a new species) . 

 cfr. IftOO Blackivelderia cilix (Walcott), idem, Vol. XXX p. 573, (description of species extended and 



more throughly discussed), 

 cfr. 191:3 Blackivelderia cih.v (Walcott), idem. Research in China, Vol, III p. I 19. 



This is the most common species of the Lincheng material. It is represented by 

 many cranidia, separated free cheeks and the associated p3'gidia. 



Cephalon transversely semicircular and rather strongly convex. Glabella trun- 

 cato-conical in outline and marked by three pairs of furrows. Posterior furrow is 

 stronglj' marked and broad, extending obliquelj^ inward and liackward. The second 

 farrow is slightly indicated by short faint lateral impressions and the anterior furrow is 

 sometimes shown only by very faint indications. Frontal limb broad and concave ; 

 frontal rim very narrow and sharply elevated; occipital furrow strongly marked broadlv 

 curving forward at the center; occipital ring broader than the furrow and convex, slightK^ 

 arching forward at the center; dorsal furrows distinct. 



Fixed cheeks narrow, their width being somewhat more than two thirds the 

 width of glabella opposite the palpebral lolx', rising regularly from the dorsal furrow to the 

 palpebral lobe; facial suture cuts the frontal border about at a right angle, extending- 

 straight back to the palpebral lobe; palpebral lobe small and elevateil. 



Associated free cheek subtriangular in outline and divided into an interior 

 convex body and the border, a sharp long genal spine very marked ; inside of which 

 the margin of the cheeks forms a broad second spine with the facial suture. 



Pygidium semicircular in outhne modeiatel}- convex and with spinose maro-in- 

 axial lobe conical with pointed terminal portion nearly reaching to the margin 



