174 RESEARCH IN CHINA. 
to the furrow just within the posterior margin; palpebral lobe small, situated about 
midway of the fixed cheek; no traces of palpebral ridges are shown; a strong, 
slightly rounded frontal rim is separated from the glabella and fixed cheeks by a 
narrow, rounded, transverse furrow; postero-lateral limb short, and marked by a 
narrow, deep furrow just within the raised posterior margin. 
Surface marked by strong pustules in all parts with the exception of the dorsal 
furrow and furrow back of the frontal rim. 
In general form this species resembles Solenopleura agno |p. 167] and Menoceph- 
alus abderus [p. 173]. It differs from the former in the shape and convexity of the gla- 
bella and broader fixed cheeks, and from the latter in the shape of its glabella, fixed 
cheeks, and frontal rim. 
Formation and Locality —Middle Cambrian: (C22) Ch’ang-hia limestone, in 
upper oolitic portion [Blackwelder, 1907a, pp. 22 and 33 (part of last list of fossils)], 
at Ch’ang-hia, Shan-tung, China. 
Collected by Eliot Blackwelder. 
Menocephalus acerius Walcott. 
Plate 16, Figures 10, 10d. 
Menocephalus acerius WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xx1x, p. 60. (Species described 
as below.) 
This species is represented by a single specimen of the glabella, fixed cheek, 
and frontal limb. ‘The glabella is moderately convex, broadly truncato-conical in 
outline, and marked by two pairs of faintly impressed, short furrows; the sides 
approach each other slightly toward the broadly rounded front; occipital furrow 
rounded and distinct; occipital ring moderately convex and a little wider than the 
occipital furrow; dorsal furrow well defined. 
Fixed cheeks convex, about two-thirds the width of the glabella; they slope 
rather rapidly downward to the frontal rim and less so to the postero-lateral limb; 
palpebral ridge not distinctly defined; palpebral lobes small; frontal rim separated 
from the glabella and fixed cheeks by a strong, narrow furrow; the rim is rounded 
and of about the same width as the occipital ring. 
Surface covered with pustules perceptible to the unaided eye. 
The cephalon of the type specimen has a length of 10 mm.; the frontal rim 
and occipital ring are each about 1 mm. in width. 
This species is referred to the genus Menocephalus on account of the small pal- 
pebral lobes, pustulose surface, and the absence of a frontal limb. It differs from 
the type form in having a less convex, more elongated glabella. 
Formation and Locality—Middle Cambrian: (C18) Dark gray oolitic lime- 
stone about 400 feet (120 m.) above the base of the Ch’ang-hia limestone [Black- 
welder, 19074, p. 33 (third list of fossils)|, in cliffs 1 mile (1.6 km.) east of Ch’ang-hia, 
Shan-tung, China. 
Collected by Eliot Blackwelder. 
Menocephalus acidalia (Walcott). 
Plate 16, Figures 8, 8a. 
Solenopleura acidalia WALCoTT, 1905, Proc. U. S. Nat. Mus., vol. xxrx, p. 89. (Species described 
essentially as below.) 
The description of M. acanthus |p. 173] applies to this species, except that it 
does not have so short a frontal limb as the latter, and its frontal rim is nearly flat 
instead of rounded. ‘The surface is smooth, with the exception of a few large, low, 
