146 RESEARCH IN CHINA. 



Genus PTEROCEPHALUS Roemer. 

 Pterocephalus asiaticus Walcott. 



Plate 14, Figures 5, 50-6. 



Pterocephalus asiatica WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxix, p. 67. (Described as a new 

 species essentially as below.) 



This species is represented by fragments of the anterior portion of the cephalon 

 and of the pygidium. Glabella truncato-conical, moderately convex, narrowing 

 gradually toward its rounded front ; surface marked by three pairs of short furrows, 

 the posterior of which separates rather small, oval lobes at the postero-lateral angles; 

 occipital furrow narrow and slightly impressed ; occipital ring of medium width and 

 nearly flat; dorsal furrow narrow, but distinctly marked. 



Fixed cheeks about two-thirds the width of the glabella opposite the palpebral 

 lobes, slightly convex, and crossed by strong, low palpebral ridges; postero-lateral 

 limbs unknown ; frontal limb very broad and slightly concave ; just in front of the 

 glabella there is a faint depression formed by a slight change in the slope of the 

 frontal limb that extends across a short distance in front of the palpebral lobe; 

 frontal rim narrow, slightly rounded, and marked by irregular striae parallel to the 

 margin. 



Surface of the glabella and fixed cheeks slightly roughened by what appear, 

 under a strong lens, to be very fine granulations ; the frontal limb is marked by irreg- 

 ular, raised lines that radiate from the front of the glabella and palpebral ridges 

 outward toward the frontal margin ; these raised lines are very irregular and more or 

 less inosculating on and near the transverse depression of the frontal limb in front of 

 the glabella and palpebral ridges. 



On a cephalon 23 mm. in length the frontal limb has a length of 1 1 .5 mm. ; and 

 the glabella and occipital ring, 11.5 mm., with a width at the palpebral lobes of 

 1 8 mm. 



Fragments of the pygidium associated with the cephalon show that it had a 

 slender, moderately convex axis, with more than eight rings, and that the pleural 

 lobes were moderately convex, flattening out on a broad, planulate margin, the 

 furrows on the axis extending out across the pleural lobes and nearly fading away on 

 the broad margin ; a faint trace of a very narrow, short pleural groove is shown on 

 two of the pleural segments. Surface of the pygidium slightly roughened by what 

 appears to be, under a strong lens, a very fine granulation. 



Formation and Locality. Middle Cambrian : (C 12) Gray limestone near the 

 top of the middle limestone member of the Kiu-lung group [Blackwelder, 19070, pp. 

 37 and 41 (part of the first list), and fig. 10 (bed 7), p. 38], 3.25 miles (5.2 km.) south- 

 west of Yen-chuang, Sin-t'ai district, Shan-tung, China. 



Collected by Eliot Blackwelder and Li San. 



Pterocephalus busiris Walcott. 

 Plate 14, Figure 4. 



Pterocephalus busiris WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxix, p. 68. (Described as a new 

 species essentially as below.) 



This species is represented by two specimens of a pygidium that is quite distinct 

 from the pygidium associated with P. asiaticus. The axis is elongate, slightly con- 

 vex, and converging uniformly to about half its width at the posterior end ; marked 

 by eight or more narrow, distinct transverse furrows, that divide it into eight or 

 more transverse rings and an elongate terminal portion. Pleural lobes slope gently 

 from the dorsal furrow down toward the margin; they are marked by the continu- 



