Scientia Sinica

No: 1 WANG: NEW SPECIES OF BRACHIOPODS [I] ~ 163

Genus Finkelnburgia Walcott 1905 Finkelnburgia meitanensis Wang (sp. nov.) (Pl. 1, J; Figs. 1-4)

Exterior: Shell large for the genus; outline subcircular, width a bit larger than length; hinge-lime narrower than the greatest width at the middle; cardinal extremities rounded to obtusely angular; lateral and front margins rounded. Surface ornamented by costellae, increasing by intercalations. There are 11 to 12 costellae in 5 millimetres at the front margin of the valve. Concentric growth lamellae crowdly developed.

Ventral valve somewhat subquadrate in outline; flatly convex in lateral profile, with the greater convexity along the median line. Interarea long, apsacline; delthyrium wide.

Dorsal valve strongly and evenly convex in lateral profile, with the greatest convexity at the middle of the valve; lateral slopes steep and gently convex. Beak low, inconspicuous as usually in the genus. No sulcus.

Ventral interior: Pseudospondylium prominent, wide, extended anteriorly into a broad and low ridge; adductor track elongately oval, elevated above the adductor scars.

Dorsal interior: Brachiophore supporting plates low, recumbent; cardinal process a low, simple ridge; pallial trunks strongly developed.

Syntypes: I.P.A.S. 7996, 7997, 7998.

Horizon and locality: Upper-most part of Loushankuan Limestone, Upper Cambrian; east side of Tuanchiakou Valley, about one mile north of Meitan City, Kweichow Province.

-€ollector: Fhe author.

Discussion: The available specimens of this species are coarsely silicified, and details of the internal characters are difficult to be observed. The surface ornamentations and dorsal interior, on the other hand, are fairly well preserved. These shells are the only fossil so far known from the barren Upper Cambrian limestone distributed widely in southwestern China.

This species differs from the other members of Finkelnburgia in its subcircular ventral valve, wide and shallow pseudospondylium and flat and high convexity of the dorsal valve.

Genus Mimella Cooper 1930 Mimella formosa Wang (sp. nov.) . (Pl. II, B; Figs. 1-8)

Shell large for the genus; roundly subquadrate in outline; hinge-line equal to about two-thirds the width of the valve; cardinal extremities and antero-