Vol.1. M.S.Chang: — Brachiopoda from the Orthis Bed (iii) 11 



of the Neichia Formation 



Davidson's fig. 3, PI. XXXIII measures thus: 

 Greatest width = 14 mm 

 Hinge line =14 ,, 



Height =10 ,, 



Proportion of height to width = 1.40 



An exterior impression of another pedicle valve (Ser. No. X205) is less per- 

 fect than No. X204. Its greatest width is 6 mm. and the height, 4.5 mm, giving a 

 proportion of height to width of 1.33. Its cardinal extremities are less extended 

 and its convexity is not so strong. Its plications are also not so numerous, but 

 they show branchings in one or two places. 



Remarks: Except for its smaller size and more numerous plications this 

 species agrees well with Orthis carausii Salter, as figured by Davidson. 



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

 X 204, X 205; Cat. Nos. 3368, 3369). 



6. Orthis neichiaensis Chang (sp. nov.) 



PI. I, Figs. 7a-d, 8a-d, ga-d, loa-b, & iia-d, and Text-figs. 1-3. 



The exterior impression of a typical brachial valve (Ser. No. X 218, PI. I, 

 Fig. 7a) is subquadrate and wider than high. The hinge line is shorter than the 

 greatest width which lies about the middle of the shell. The valve is moderately 

 fiat with a sinal dejjression along the central portion. The surface is ornamented 

 by about thirty-three simple and rounded plications with slightly wider interspaces 

 which are occupied by very fine longitudinal and transverse lamellose strige. The 

 sinus is bounded by two plications which bifurcate about two mm. below the beak. 

 In its center are found four plications which are a little stronger than the others. 

 The arrangement of the sinal plications is shown in Text-Figure 1. 



Te.xt-Fig. I. Arrangement of the sinal plication in specimen No. X 218. 



