(ii) 43 Palxontologia Sinica Ser. B. 



except for 6 sharply impressed annular lines which are 5-7 mm. apart; the impressions are 

 somewhat wavy, probably owing to the secondary deformation of the entire shell. The 

 lines at first sight appear to be the suture lines of the septa, but in reality coincide with 

 them only partially." "The septa are traversed at the center by a broad (12 mm. in 

 diameter) empty tubular space, which is completely shut off from the interior of the 

 camene by means of the septal necks, these being very long and extending beyond the 

 preceding septum. There is absolutely no organic deposit in the interior of the shell." 

 Even though no such impressed annular lines are seen on the surface of our specimens as 

 is the case in that of the Japanese authors, the large endoconch, long tubi, closely set 

 ectosepta and some other properties show that Yabe and Hayasaka's form is really the 

 same as the present species. Reed had described one specimen from the Ordovician bed 

 of Shih-tien in Yunnan and called it Cameroceras.^ In reality it also belongs to the 

 present species. The original diagnosis given by Reed is as follows. 



"The shell appears to have been straight, slightly elliptical in cross section, cyl- 

 indrical, very slowly tapering. A large undivided body chamber seems to be present, 

 and on it traces of fine concentric lineation are visible, this body chamber measures 

 about 33 mm. in length and has a diameter of about 26 mm. The septate portion of the 

 shell measures just 20 mm. in length and contains 11 septa. The septa, therefore are 

 closely approximate, being rather less than 2 mm. apart; they are thin, horizontal, but 

 very slightly undulated. A transverse section made of the lower end shows that the 

 shell is elliptical with diameters of 21 mm. and 25 mm., and there is a very large siph- 

 uncle about 14 mm. in diameter, situated nearer the ventral than the dorsal margin." 



Comparison: This species is quite similar to the previously described Vaginoceras 

 naichianense, but after closely studying it we can see that the present form has the endo- 

 conch much larger and the ectosepta much closer. Moreover, the interior of this form is 

 absolutely free from organic deposit, which is present in the other species. It also 

 resembles Vaginoceras vaginatum Schlotheim, but may be distinguished from it by the 

 position of the endoconch, which is marginal in Schlotheim's species. 



Horizon and Locamty: From the upper part of Neichiashan formation near 

 Sin-tan. (Coll. J. L. Smith and C.Y. Hsieh respectively) 



Vaginoceras uniforme Yli (sp. nov.) 

 Plate II., Figs. 8a-b, 9; Plate V., Figs. 4a-b. 



Outer shell straight, cylindrical, cross section elliptical with a moderately large 

 endoconch submarginal to the ectoconch. 



I. loc. cit. 



