Fig. 6. Orthoceras cf. politum M'Coy. Nat. size P- .52 



A natural weathered section with a part of siphuncle preserved at the 

 upper end of the specimen, 



Loc: — Ta-hung-shan, Nan-chang-hsien, N. Hupeh. (N.R.I. Cat. No. 32) 



Fig. 7. Orthoceras yangtzeense Yii. Nat. size p. 59 



External view of an internal mould of the shell, showing the V-shaped 

 lobes formed by the septal sutures. 



Loc: — Near Sin-tan, Tze-kuei-hsien, W. Hupeh. (G.S.C. Cat. No. 2851) 



Fig. 8. Orthoceras yangtzeense Yii. Nat. size p. 59 



8a. External view of an internal mould, showing the V-shaped lobes. 



8b. End view of the same specimen, showing the size and form of the 

 subraarginal siphuncle at the opposite side of the V-shaped lobes. 



Loc: — Near Sin-tan, Tze-kuei-hsien, W. Hupeh. (G.S.C. Cat. No. 2852) 



(II) 83 



