Scientia Sinica

No. 1 WANG: NEW SPECIES OF BRACHIOPODS [I] 161

Ventral valve gently convex; umbo swollen; beak small, a little arched.

Dorsal valve flatly convex, with most convexity in the umbonal region; beak low, inconspicuous; sulcus wide and angular, extending a little anterior from the beak and deepening toward the front.

The median part of the shell is marked by three strong, subangular plications extending from the beak to the anterior margin. On each side of the median part there are usually two similar plications, the outer one being much weaker. The postero-lateral flanks are unplicated but are marked by very fine, subequal costellae. The anterior half of each strong plication is obscurely fasciculate.

Measurements (mm)

| Length | Width - © | Hinge-width Ventral valve 7991 DD) 94 . 7.6 Dorsal valve 7992 5.6 9:4 10.2

Syntypes: I-P.A.S. 7991, 7992, 7993.

Horizon and locality: Upper Cambrian; Wanchiachai, east of the Yellow River, 25 miles north of Piankwan, Shansi Province. ~

Collector: F. H. Chia.

Discussion: Owing to the poor preservation, the characters of the specimens are not entirely clear. It is tentatively placed to the genus Apheoorthis | on account of its fasciculate surface plications. Apheoorthis costalis recalls A. meeki) and A. oklahomensis"!, both occurring in the Upper Cambrian of North America, but differs from the two species in the possession of a very broad and deep sulcus in the dorsal valve. The surface ornamentation of this new species can be recognized by the few strong and prominent plications _ which tend to flatten and bifurcate toward the front.

Genus Glyptorthis Foerste 1914 Glyptorthis simplex Wang (sp. nov.) (Pl. 1, H; Figs. 1-5)

Extertor: Shell moderately large for the genus; subquadrate in outline: hinge-line straight, as wide as or a little narrower than the greatest width; cardinal extremities square or nearly so; valves subequally biconvex, the ventral valve having greater convexity; ornamentation multicostate; costx angular,

strong, increasing by bifurcation and implantation; imbrications delicate, only developed in the anterior part of the shell.