Page:Walcott Cambrian Geology and Paleontology II.djvu/147

NO. 4 Coosia limbatum (Angelin); it differs in having a slightly convex or rounded frontal limb and proportionately narrower glabella. The pygidium is quite different in outline; the rounded indented posterior margin of A. limbatum is represented by a deep notch that gives a bilobed appearance to the very broad margin; the axial lobe is also longer and broader than that of A. limbatum. The doublure of the pygidium extends close up to the termination of the furrows of the pleural lobe. The pleural lobes of the thoracic segments have a narrow, strong furrow that extends from the inner, anterior margin diagonally across nearly to the posterior margin of the backward curving, slightly falcate ends of the segment.

The stratigraphic position of this species is about 250 feet (79 m.) above the zone of Anomocare latelimbatum Angelin.

The specific name is given in recognition of the excellent work done by Li San, who assisted Professors Willis and Iddings in their collecting.

Formation and locality.—Middle Cambrian: (35q) Fu-chóu series; about 200 feet (61 m.) above the white quartzite, 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.

Anomocarella, 1905, Proc. U. S. National Museum, Vol. 29, p. 54. (Genus characterized.)

Anomocarella was proposed to include species from the Middle Cambrian of China, that differ from Anomocare in the absence of glabellar furrows and the presence of a relatively narrow, flattened frontal rim. The sides of the glabella are parallel, palpebral lobes of medium size, and palpebral ridges more or less clearly defined. The associated pygidium has a narrow, conical axis, marked by several transverse furrows which extend out on the pleural lobes and more faintly on the sloping rim.

Genotype.—Anomocarella chinensis Walcott.

Observations.—The type of this genus has ten segments in the thorax with a broad pleural furrow that starts near the inner anterior margin of a segment, broadens very rapidly and extends out beyond the geniculation before gradually narrowing to a point. In Anomocarella smithi (pl. 17, figs. 3, 3a) there are twelve segments in the thorax with the same type of pleural furrow.