(ii) 60 Palxontologia Sinica Ser. B. 



Horizon and Locality: The upper Neichiashan formation yields this form near 

 Sintan, Tze-kuei-hsien (Collections: J. L. Smith and C. Y. Hsien respectively) 



Orthoceras? wongi Yu (sp. nov.) 

 Plate v., Fi^'s. roa, b. 



The weathered surface of this specimen appeal's to be annulated outside. But 

 after a careful study we find that all the transverse depressions are just in the positions 

 of septal sutures. In another smaller shell probably belonging to the same species, the 

 surface is rather smooth, though it also slightly exhibits a longitudinal undulation to 

 some extent. It may be concluded that the annulation-like sculpture is probably the 

 result of the weathering. Shell straight, cylindrical, having a length of about 40 mm. 

 It has a sub-elliptical section. The expansion of the conch is slow, about i in 10 or 

 more. Both the extremities are missing. 



The septal sutures are slightly undulating. The septal distances are approximate 

 and uniform, being about 1/8 the shell diameter, which is also the concavity of the 

 septa. In actual measurement the septa are 3 mm. apart throughout the whole frag- 

 ment, which has a longer diameter of 20 mm. at the lower end and 24 mm. at the upper. 



The siphuncle is subcentral, cylindrical, being 3.5 mm. in diameter. It is circular 

 in section. It is a remarkable thing that the septal necks assume the character of those 

 in Holochoanites, extending beyond the preceding septa for a little distance. The in- 

 terior of the siphuncle is empty. A few camen-e are partly filled with the crystalline 

 calcite. 



Remarks: The siphuncle of this form is not very large, suggesting the ordinary 

 size of an Orthoceras, though having such long septal necks. I hesitate to consider this 

 as another distinct genus. The generic name, now applied to our shell is only provisional. 



Horizon and Locality: Same as the preceeding species, with which the present 

 form is associated. 



Orthoceras sp. 



Plate IX., Fig. 3. 



Shell small, slender, slightly curved, enlarging very slowly. The transverse 

 section is nearly circular. The initial portion as well as the body-chamber unknown. 

 Rate of increase 1:27. 



