Page:Walcott Cambrian Geology and Paleontology II.djvu/155

NO. 4 The casts of the outer surface indicate that it was smooth or minutely granulose.

Observations.—This species appears to be quite distinct from any that has been described. The quadrangular glabella with nearly parallel sides distinguishes it from Bathyuriscus howelli Walcott and B. productus (Hall and Whitfield).

Formation and locality.—Middle Cambrian: (36g), (36h) and (35o) Fu-chóu series; shales about 130 feet (40 m.) above the white quartzite 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.

Dorsal shield longitudinally oval in outline, moderately convex. Cephalon semicircular in outline; a little more than one-third of the entire length of the dorsal shield; bordered by a nearly flat or slightly rounded margin that passes at the genal angle into a moderately strong genal spine; within the genal spine a rounded posterior border is separated from the fixed cheek by a rounded, clearly defined furrow; the interborder furrow is shallow and rounded. Cranidium moderately convex and roughly subquadrate in outline; the frontal limb is slightly convex and, with the anterior portion of the glabella and the front margin, forms a gentle slope that is broken only by the slight dorsal furrow in front of the glabella and the shallow intermarginal furrow; the frontal limb merges on the sides into the fixed cheeks which are a little less than one-half the width of the glabella; posteriorly the fixed cheeks merge into relatively small postero-lateral limbs; palpebral lobe narrow and extended in front as a low ridge that crosses the fixed cheek to the dorsal furrow near the antero-lateral angle of the glabella; that portion of the palpebral lobe above the eye is about one-fourth the length of the cephalon.

Glabella large, slightly narrower in front than at the occipital furrow; sides nearly straight and slightly converging, frontal margin broadly rounded; surface marked by very faint impressions of three pairs of glabellar furrows, which can only be seen where the surface is very perfectly preserved. Occipital ring about as wide as the frontal margin and separated from the glabella by a shallow furrow that terminates on the side slightly in advance of the posterior intermarginal furrow. Free cheeks about as wide opposite the eye as the fixed cheeks; eye lobe about one-fourth the length of the cephalon. Postero-lateral angle continued backward into a moderately strong