Vol.1. M.S.Chang: — Brachiofoda from the Orthis Bed (m) 9 



of the Neichia Formation 



to the anterior part, being more pronounced, thus suggesting the presence of a slight 

 fold. The beak is small and shows little incurvature. The surface ornamentation 

 consists of twenty-four simple and round plications, the middle six being more 

 strongly developed. Near the beak the interspaces between the plications are very 

 narrow or nearly absent, but they expand very quickly, till at the anterior part of 

 the shell they measure one mm. or a little more. They are also occupied by two 

 or three fine longitudinal striae. 



Measurements : 



Greatest width = 13 mm 

 Hinge line = 12 mm 



Height =11 mm 



Proportion of height to width = 1.18 



Another specimen of the same species (Ser. No. X232, PI. I, Fig. 4a) has 

 part of the right side of the shell broken away. It is smaller and a little more 

 convex, but in other respects agrees with the holotype. 



Remarks: This species resembles Davidson's Orthis calligramma more than 

 Orthis calligramma var. sinensis does. It differs only in its smaller size and more 

 numerous plications. 



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

 Nos. X 202, X 232; Cat. Nos. 3365, 3366). 



4. Orthis carausii Salter, var. nanchanghsiensis Chang (var. nov.) 



PI. I, Fig. 5a-d. 

 cf. 1869. Orthis carausii Salter, MS. Davidson, British Fossil Brachiopoda, Pt. VII, No. Ill, p. 229, 

 pi. XXXIII, figs. 1-7. 



This species is represented by a broken exterior impression of the brachial 

 valve. It is subsemicircalar, considerably wider than high, and has the hinge line 

 equal to the greatest width. The valve is almost flat, with a gentle sinus covering 

 about seven plications along the middle. The surface is marked by about thirty- 

 two round plications which show branchings and bifurcations here and there. Ihe 

 plications in the central part are stronger than those on the sides, thus giving the 

 shell a three-zoned appearance. The interspaces are wider and contain fine long- 

 itudinal as well as faint transverse lamellose striee. 

 Measurements : 



Greatest width — 18 mm 



Hinge line = 18 mm 



Height = 11 mm 



Proportion of height to width = 1.64 



