Vol. I. C. C. Yu — Ordovician Cephalopoda of Central China (ii) S7 



Comparison: This species somewhat approaches to Cameroceras hrainerdi 

 Whitfield' in some respects, but the former has the tapering more rapid and the 

 endoconch not marginal as in the latter form. It may also be compared with Camer- 

 oceras hsiehi, but differs from it in having the subcentral and elliptical endoconch. 



Horizon and Locality: This form was obtained from the same horizon as the 

 preceding species near Sin-tan. (C. Y. Hsieh Coll.) 



Cameroceras sp. 

 Plate II., Fig. 3. 



This form is too fragmentary for specific determination. The septal portion 

 preserved only contains four cameriie, and has a length of 45 mm. Owing to the fact 

 that the specimen is much eroded, the cross section of the ectoconch and the rate of 

 tapering can not be determined. 



Ectosepta gently concave, having a depth of nearly 2/3 that of the camera. The 

 ectoseptal interspaces increase very slightly in distance, being nearly equal to 2/5 the 

 diameter of the outer shell. The septate chambers are wholly empty. The organic 

 stereoplasmic deposit occurs only along the interior sides of some cameriij. 



The endoconch is marginal. Since it has also been greatly rubbed, neither the 

 transverse section nor the size of the inner shell may be determined with any certainty. 

 Nevertheless, from what remains we can tell that it is confined externally by the presence 

 of an endotheca and filled internally with the calcite deposit. The tubi extend apically 

 in an irregular rnanner and the endotheca also assumes the wavy appearance, following 

 the direction of the tubi. 



Undoubtedly the present specimen belongs to the genus Cameroceras in having 

 the characteristic endotheca. But its other important properties are too Uttle known, 

 hence its specific determination is impossible 



Horizon and Locality: Upper part of Neichiashan formation near Sin-tan. 



I. Ruedemann: Cephalopoda of the Beekmantown and Chazy Formations of the Champlain 

 Basin, p. 405, pi. L figs. 5-6; pl- 2, fig. i. 



