(in) 16 Palmontologia Sinica Ser. B. 



The shell is subquadrate and wider than high, the hinge line being slightly 

 less than the greatest width and the front regularly rounded. The pedicle valve is 

 strongly convex and a little swollen. The beak is high and a little incurved. The 

 rostral cone is highly developed and divided into one median and tw^o lateral lobes 

 by two deep and well-marked parallel grooves. The surface is mostly smooth, 

 only marked by plications on the anterior two or three mm. of the mold^. The 

 number of plications is not known on account of the broken nature of the specimen, 

 but that there are intercalations and bifurcations seems to be certain. 



Measurements : 



Greatest width = 15 mm 

 Hinge line =14 ,, 



Height =11 ,, 



Length on curvature = 15 mm 

 Proportion of height to width — 1.36 

 Shell index = 0.93 



x\nother specimen (No. X 206 PI. II, Figs. 6, 6a) shows some difference from 

 the above. It is less convex and the hinge line seems to be equal to the greatest 

 width. The plications are simple and have no intercalations. A high triangular 

 cardinal area is also suggested. 



Remarks: This species agrees well with the descriptions by Reed. It differs 

 from OTthis calligramma in being more convex and having plications of a more 

 complicated character. 



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

 Nos. X 208, X 206; Cat. Nos. 3383, 3384). 



Genus PleCTORTHIS Hall and Clarke 



11. Plectorthis sp. i. 



PI. II, Fig. 7a-d. 



cf. 1917. Orihis [Plectorthis) ardiiiilhinoisis Reed. The Ordovician and Silurian Brachiopoda of the 

 Girvan district, p. 831, pi. V, figs. 33-39. 



This species is represented by the exterior impression of the pedicle valve. 

 It is transversely elongated or Spirifer-like in form, the width being more than 

 twice the height. The hinge line is equal t j the greatest width and part of the hinge 



I. Reed figures a similar mold (pi. V. fig. 13), but his other figures show that the exterior is well 

 phcated. 



