DESCRIPTION OF GENERA AND SPECIES. 121 



surface. The pygidium of B. cilix [plate 9, figs. 6b-c] differs from that of B. sinensis 

 [plate 9, figs. 5^, 5g] in having the sixth spine on each side much longer than the 

 others, also in having a stronger axial lobe and less distinctly defined border. The 

 comparison of B. cilix with species referred to the genus Teinistion is referred to 

 under the description of the genus Blackwelderia. 



Formation and Locality. Middle Cambrian: (C55) Just below the Ch'au- 

 mi-tien limestone in the Ku-shan shales [Blackwelder, 19070, p. 43], in isolated 

 hills at an elevation of 380 feet (114 in.) above the Won-ho, 12 miles (19 km.) south 

 80 east of Tsi-nan, Shan-tung; also (C73), conglomeritic limestones near the top of 

 the Ki-chou limestone [Willis and Blackwelder, 1907, p. 145, fourth list of fossils], 

 4 miles (6.4 km.) east of Fang-lan-chon, Shan-si, China. 



Collected by Bailey Willis and Eliot Blackwelder. 



Blackwelderia sinensis (Bergeron). 

 Plate 9, Figures 5, 5<j-g. 



Calymmene ? sinensis BERGERON, 1899, Bull. Soc. geol. de France, 3d ser., vol. xxvn, p. 500, 



plate 13, figs. T, 2, and text figs, i, 2, p. 501. (Species discussed and described from fragments 



of cranidium.) 

 Olenoides leblanci BERGERON, 1899, idem, p. 506, plate 13, figs. 5, 6, and text-figs. 5, 6, p. 506. 



(Species discussed and described from pygidium.) 

 Slephanocare sinensis MONKE, 1903, Jahrb. konigl. Preuss. Geol. Landesanstalt und Bergakademie, 



vol. xxm, pt. i, 1902, p. 142. (Discusses species.) 

 Blackwelderia sinensis (Bergeron), WALCOTT, 1906, Proc. U. S. Nat. Mus., vol. xxx, p. 573. (Places 



Calymmene I sinensis Bergeron as the type of the genus Blackwelderia.) 



Cephalon transversely semicircular, rather strongly convex, most elevated at 

 the palpebral lobes; frontal border or rim nearly transverse in front of the glabella, 

 rounding gently to the postero-lateral angles; it is narrow and somewhat elevated 

 in front, becoming more rounded at the sides; it continues around the postero- 

 lateral angle to unite with a narrow, slightly defined posterior border. A postero- 

 lateral spine projects backward and slightly upward from a point on the margin a 

 little in advance of where the facial suture cuts the margin. 



Glabella large, truncato-conical in outline, and marked by a posterior pair of 

 furrows that extend obliquely inward so as to outline a small triangular lobe that is 

 connected by a low ridge with the fixed cheek ; the middle pair of furrows is short and 

 slightly impressed; the anterior pair of furrows is very short, and usually not clearly 

 defined; occipital furrow transverse, rounded, of medium width, and not very deep; 

 occipital ring of medium width, curving slightly forward toward the sides, and gently 

 convex ; dorsal furrow clearly defined at the sides of the glabella except at the ridge 

 connecting the posterior lobe of the glabella and the fixed cheek, where it is very 

 shallow in most specimens; in front of the glabella there is little more than an 

 angle formed by the union of the downward slope of the glabella and the outward 

 slope of the frontal limb. 



Fixed cheeks nearly as wide as the glabella opposite the palpebral lobes; they 

 rise from the dorsal furrow to the palpebral lobes and slope with a gentle curvature 

 downward to the frontal limb and extend with a very slight slope to the strong fur- 

 row within the posterior margin; a slightly defined palpebral ridge starts from the 

 anterior margin of the palpebral lobe and extends part way across the fixed cheek 

 before disappearing; postero-lateral limb about one and one-half times as long as the 

 width of the glabella at its base, and back of the palpebral lobes a little more than 

 one-third the length of the cephalon ; palpebral lobes about one-fourth the length of 

 the cephalon, elevated at the outer border and quite prominent ; frontal limb narrow, 



