(ii) 50 Palxontologia Sinica Ser. B. 



Septa gently concave, so far as observed, with a concavity equal to one half of 

 the camera. The septal distance increases irregularly as the shell expands in diameter, 

 having a depth varying from 12 mm. to 22 mm., where the corresponding diameters of 

 the tube are 18 mm. and 35 mm. respectively. 



The siphuncle is narrow, and equal to one tenth the diameter of the shell. It is 

 eccentric, its border touching the central axis of the conch. It is enclosed by the septal 

 necks, which, as determined from a few of them which are clearly shown in the longitu- 

 dinal section, are comparatively short, about one third the depth of the camera. There 

 is no trace of deposits in the siphuncle. All the camerae contain the white crystalHne 

 lime in addition to the stereoplasmic lining. 



Comparison: At first sight this specimen scarcely differs in aspect from 

 Orthoceras sp.^ figured by Woodward, but after close examination our shell may be 

 distinguished from Woodward's shell by the excentric siphuncle, the shorter septal necks 

 and the more remote septa. It closely resembles Orthoceras chinense Foord var. kuang- 

 chiaoense except for the position of the siphuncle and some other minor features. There 

 fore, I am inclined to regard this form as another variety of Foord's species. 



Horizon and Locality: This shell was collected from the bed just underly- 

 ing the reddish limestone at a place not far from Wang-chia-sze, Chung-yang-hsien. 



Orthoceras chinense var. equiseptatum Yii (var. nov.) 

 Plate VIII., Figs. 3-5; Plate IX., Figs. la-b. 



Shell (PI. VIII., Fig. 3) subcylindrical, robust, circular in cross section. Apical 

 portion not observed. The diameters at the two extremities of this fragment are 34 

 mm. and 54 mm. respectively, the distance between them being 133 mm. The rate of 

 increase is in the proportion of i to 6.5. Test not exposed, 



The preserved part of the living chamber is about 70 mm. in length and 56 mm. in 

 diameter at its base. Seven complete adjacent camenis have been recognized, varying 

 slightly in their depth. Thus each of the lowest two camera measures 20 mm. in 

 length, while above these the .septa are separated by a distance of 17 or 18 mm. Still 

 higher up the camera; assume again the same depth as the lowest one. In general they are 

 of nearly the same depth, this being greater than r/2 the diameter of the shell at the lower 

 preserved end and less than 1/2 at the upper. The last camera is shallower than any of 



r. S. P. Woodward: Quart. Journ. Geol. Soc, Vol. XII, p. 378, pi. VI, fig. r. 



