Scientia Sinica

160 SCIENTIA SINICA Vol, V

(Pl. 1, F; Figs. 1-4)

Shell large, attaining 40 mm in mature specimen; narrowly elliptical to sub-oblong in outline; anterior end rounded to subtruncated; posterior margin gradually acuminated; lateral profile equally convex, lenticular. Surface ornamented by strong, coarse, undulated lines.

Dimensions (mm): Length 21.8; width 12.3; thickness 5.6.

Holotype, I-P.A.S. 7987, paratype, I.P.A.S. 7988.

Horizon and locality: Kelimoli Limestone, Lower Ordovician; Latsatsung, south of Chotzeshan, Ordos, Inner Mongolia.

Collectors: §S. C. Kwan and Y. H. Lu.

Discussion: This new species can be recognized by its large size and narrowly elongate form. In size and outline, this species suggests relationship with Ectenoglossa nympha (Billings)“! from the Middle Ordovician of North

America. But no trace of “teeth” can be observed in the internal mold of our specimen.

Genus Paterina Beecher 1891 Paterina talingensis Wang (sp. nov.) (PINT, TV; Bigs: 1-2) Shell minute; outline broadly ovate; ventral valve depressed subconical; beak highly arched, marginal, curving abruptly backward and downward to form a steep false area. Dorsal valve slightly convex, with the posterior margin

nearly straight and a little narrower than the greatest width of the valve. Surface marked by fine concentric irregular lines.

Syntypes: I.P.A.S. 7989, 7990.

Horizon and locality: Manto Shale, Lower Cambrian; Taling, east of Kaochiatsui Station, Penhsi District, Liaoning Province.

Collectors; Members of the Taitzeho Party, 1950.

Discussion: This species differs from Paterina lucina Walcott”, a Middle Cambrian species known from China, in its less convex ventral valve and more rounded outline.

Genus Apheoorthis Ulrich and Cooper 1936 ° Apheoorthis costalis Wang (sp. nov.) (Pl. 1, G; Figs. 1-3)

Shell of medium size for the genus; width greater than length, with the hinge-line forming the greatest width of the shell. Cardinal extremities acute; lateral margins broadly rounded.