222 RESEARCH IN CHINA. 
Surface of specimens preserved in the limestone nearly smooth or marked by 
very minute shallow pits. 
Dimensions.—A dorsal shield 30 mm. in length has the following dimensions: 
Cephalon: mm. 
[Poi .d ee rer rers Coren cesta omar cm eae ett 5 ote oo co 9 cece II.O 
Length of eyelobes 26,25 scthoore oo nttensia shee nta sete tel retaliate ae ce horas meee Nee coeur enema NG 
Width at posterior marr inis cay ee cere en eee a eee an 20.0 
‘Width of glabella at posterior marine ncee ironies ete eee eee 6.0 
Thorax: 
Length osc ein See ae. Se IG ero ac ore ee ener eee 1220 
Width at fourth segment jc: teens wea cenit tee Cee ee er ee 19.0 
Width of-axtal loberat first segment. cose = are ie erets tetera rete eect eet ee tee 5.5 
Width of axiallobesatininth segments Grn tate eerie aerate ee ane 4.0 
Pygidium: 
Tyemg tb iia. a itp rence iw nis, a 0a A ioral GM OES <a ts. Pen teak en eo 7.0 
Width atunion with thorax 22. 7ar ee ee eee ee ae eee ee eee 12.0 
Fragments of this species are quite abundant in the limestones and interbedded 
shales. A few entire specimens are found in a fine argillaceous shale a short distance 
above the white quartzite at the base of the section, and it is from the best speci- 
mens of these that the above description was drawn, together with specimens of 
the cranidium in the limestone. 
In general outline and appearance Asaphiscus iddingst approaches the type of 
the genus, A. wheeleri Meek [Walcott, 1886, plate 31, fig. 3]. Asaphiscus iddingsi 
has a genal spine, a longer eye-lobe, a proportionately shorter cephalon, and nine, 
instead of eight, segments in the thorax. 
Formation and Locality —Middle Cambrian: (35r and 36e) Fu-chou series, shales 
interbedded with limestones near the base of the series just above the white quartz- 
ite [see Blackwelder, 1907), p. 92, for general section giving stratigraphic relations]; 
collected in a low bluff on the shore of Tschang-hsing-tau Island, east of Niang- 
niang-kung, Liau-tung, Manchuria, China. 
Collected by J. P. Iddings and Li San. 
Genus ILLZNURUS Hall. 
Illenurus canens Walcott. 
Plate 23, Figures 3, 3a-c. 
Illenurus canens WALCOTT, 1905, Proc. U.S. Nat. Mus., vol. xxrx, p.96. (Described as a new species 
essentially as below.) 
Cephalon, exclusive of the free cheeks, subrhomboidal in outline, moderately 
convex. Glabella subquadrate, moderately convex, length and width the same, 
without perceptible occipital or dorsal furrows; palpebral lobes small, with their 
anterior end opposite the center of the glabella; frontal margin broadly rounded; 
postero-lateral limbs short and subtriangular in outline; the facial suture, cutting 
the frontal rim on a line with the base of the palpebral lobe, passes directly to the 
anterior margin of the palpebral lobe; it encircles the latter, and then, curving 
gently outward, passes in an almost direct line to the postero-lateral margin of the 
postero-lateral limb. 
Surface minutely punctate under a strong lens. 
The pygidia associated with the cephalon parts are rounded subtriangular in 
outline, and about two-thirds as long as the width of the anterior margin, rather 
convex, and marked on the interior of the cast by a faintly defined, rather narrow 
axis, and very slight traces of ten or more transverse furrows on the axis, that are 
more faintly indicated for a short distance on the pleural lobes. 
The largest cephalon in the collection has a length of 14 mm., with the same 
width at the palpebral lobes; a pygidium 14 mm. in length has a width of 20 mm. 
