146 RESEARCH IN CHINA. 
Genus PTEROCEPHALUS Roemer. 
Pterocephalus asiaticus Walcott. 
Plate 14, Figures 5, 5a—b. 
Pterocephalus asiatica WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxrx, 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 striez 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 11.5 mm.; and 
the glabella and occipital ring, 11.5 mm., with a width at the palpebral lobes of 
18 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: (C12) Gray limestone near the 
top of the middle limestone member of the Kiu-lung group [Blackwelder, 1907a, 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. xxrx, 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- 
