Vol.1. M.S.Chang: — Brachiopoda from the Orthis Bed (iii) l7 



of the NeicMa Formation 



area with a smooth surface is also shown. The shell is convex, the convexity being 

 more pronounced in the posterior two-thirds of the central region, while the an- 

 terior third is abruptly deflected downwards, with a rather strong geniculation. 

 The sides of the delthyrium are supported by delicate subparallel dental plates 

 which in the impression of the exterior, suggest a rectangular rostral cone with 

 sides about one mm. in length. The surface is covered by about forty rounded 

 plications, many of them showing intercalations. Concentric lamellose strias are 

 also present. 



Remarks: The plications and shape of this species suggests Plectorthis 

 ardmillanensis Reed, but its transverse elongation and the absence of longitudinal 

 striae within the interspaces of the plications at once separates them. 



Horizon and Locality: Occurs with the preceding. Coll, C. C. Yii. (Ser. 

 No. X212; Cat. No. 3385). 



12. Plectorthis sp. 2 



PI. II, Fig. 8a-d. 

 cf. 1869. Orthis elegantula Dalman : Davidson, British Fossil Brachiopoda, Pt. VII, No. Ill, p. 211, 

 pi. XXVII, figs.- 1-9, (with literature references). 



This species is also represented by an exterior impression of the pedicle 

 valve. It is cardiform or has the shape of an inverted isosceles triangle. It is a 

 little wider than high and has the greatest width at the hinge line. The beak 

 region is filled by the broken rostral cone, m.argined by the delicate subparallel 

 dental plates. The shell is convex, being most pronounced along the central region 

 thus giving a steeply crescentiform section. The surface is ornamented by round 

 and bifurcating plications, the number of which is indeterminable on account of 

 the broken conditions of the shell. In the center of the anterior portion there are 

 about five plicae in two mm. The measurements are six mm. for height and seven 

 mm. for width. 



Remarks: The specimen is too poor for specific identification. 



Horizon and Locality: Occurs with the preceding. Coll. C. C. Yii (Ser. 

 No. X 214; Cat. N. 3386). 



Genus DaLMANELLA Hall and Clarke 



13. Dalmanella cf. elegantula (Dalman) 



PL II, Figs, ga-d & loa-d. 

 cf. 1869. Orthis elegantula Dalman: Davidson, British Fossil Brachiopoda, Pt. VII, No. Ill, p. 211, 



pi. XXVII, figs. 1-9, (with literature references). 

 cf. 1892. Orthis elegantula Dalman. Hall and Clarke, Palaeontology of New York, Vol. VIII, Pt. I, pi. 



Vc. fi^s. 15-ig. 



