Scientia Sinica

No. 1 WANG: NEW SPECIES OF BRACHIOPODS [1] 175

Ventral valve shallow, gently and flatly convex; elevated a little in umbonal region, depressed anteriorly by very broad shallow sulcus, equal to about three-fourths the width of the valve; anterior half of the sulcus strongly geniculate at right angle and continued forward as a short lingual prolongation; beak narrow and acutely pointed; foramen minute, circular.

Dorsal valve strongly convex, with the greatest convexity near the anterior margin whence the surface descends steeply and abruptly toward the lateral margins and slopes gradually toward the beak; fold short, equal to only onethird the length of the valve, bending abruptly to meet the sulcus; beak concealed. ,

Posterior portion of the shell smooth; anterior margin marked by strong, short, angular plications, the number averaging 6 on the fold, 5 in the sulcus and 2 or more obsolete ones on each lateral slope.

Dimensions (mm): Length 6.7; width 7.9; thickness 5.6. Holotype, I.P.A.S. 8018.

Horizon and locality: Penhsi Series, Middle Carboniferous; south of the second tunnel, Tsuichiakou, Yentai Colliery, Liaoning Province.

Collectors: Y. H. Lu, S. W. Tang, and the author.

Discussion: This species agrees both in size and number of surface plications with Wellerella dekalbensis Dunbar and Condra"®! but differs strikingly from the latter in having a width greater than its length and in having a less pointed ventral beak. Externally, it is easy to separate the present form from W. dekalbensis by its much shorter surface plications which originate farther anterior to the middle of the valve. .

Genus Zygospira Hall 1862 Zygospira kueichowensis Wang (sp. nov.) (Pl. IV, A; Figs. 1-5)

Size small; valves subequal in depth, biconvex; outline subcircular; hingeline narrow, curved; cardinal extremities and antero-lateral angles rounded. Surface marked by sixteen or more subrounded, sharp costae; all costae originate from the beaks with few secondary costae added in the antero-median

parts of the shell.

Ventral valve moderately convex, with the greatest convexity along the postero-median region, thence it slopes gradually toward the lateral and anterior margins; beak elongate, strongly incurved.

Dorsal valve evenly and broadly convex, lateral flanks fairly swollen; umbonal region a little sulcate; beak concealed by the ventral one.