PLATE IX. 



Fig. I. Orthoceras chinciise Foord var. equiseptatum Yu. Nat. size p. 50 



la. Longitudinal section, showing the septal distances and the septal necks. 



lb. Cross section, with a central circular siphuncle. 



Loc:--Heh-chia-tzui-tze, Chang-chia-chi, Chung-chei-hsien, N. Hupeh. 

 (N.R.L Cat. No. 24) 



Fig. 2. Orthoceras deiisiuii Yii. Nat. size p. 58 



A natural weathered section of a young stage of the shell, showing the 

 numerous septa at the apical portion. 



Loc: — Lin-chia-chung, Kung-chia-wang, I-cheng, N. Hupeh. (N.R.L 

 Cat. No. 28) 



Fig. 3. Orthoceras sp. Nat. size p. 60 



Lateral view of the specimen, showing the oblique septal sutures. 



Loc: — Pei-ting-tze, Hu-chia-chi, Chung-hsiang-hsien, N. Hupeh. 

 (N.R.L Cat. No. 33) 



Fig. 4. Orthoceras sp. Nat. size p. 61 



A natural polished section. The siphuncle has been completely 

 eroded away. 



Loc: — Between Cha-ti-pu and Chang-chia-chiao, Hsien-ning-hsien, SE. 

 Hupeh. (N.R.L Cat. No. 34) 



Fig. 5. Discoceras enrasiaticum Freeh. Nat. size p. 64 



Side view of a characteristic shell, showing the costos on the surface 

 of the shell and the septal sutures as exposed at the last half volution 

 where the test has been broken away. 



Loc: — Nei-chia-shan near Sin-tan, Tze-kuei-hsien, W. Hupeh. (G.S.C. 

 Cat. No. 2856) 



Fig. 6. Discoceras enrasiaticum Freeh. Nat. size p. 64 



6a. Side view of a small specimen, showing the volutions and the costfp 

 on the surface of the shell. 



6b. Transverse section of same, showing the whorls subquadrate in 

 section and the siphuncle marginal to the internal side. The section 

 is taken across the middle part of the umbilicus. 



Loc: — Nei-chia-shan near Sin-tan, Tze-kuei-hsien, W. Hupeh. (G.S.C. 

 Cat. No. 2857) 



(11) 100 



