^^^- ^- C. C. Yu—Ordovician Cephalopoda of Central China (ii) 11 



that formation have not been found in this upper division, and though their lithological 

 characters also differ to some degree, nevertheless some cephalopods from this division 

 are of the type of those common in the upper part of Neichiashan formation on the 

 one hand and others correspond to those obtained from the top of Tafang hmestone 

 on the other. It is quite possible to say that this upper division may be compared 

 with the upper part of Neichiashan formation. The cephalopods secured from this 

 division include the following species : 



Endoceras leei Yd 



Vaginoceras wahlenbergi Foord. var. cylindrica Yii 



V aginoceras endocylindricum Yii 



Vaginoceras peiyangense Yii 



V aginoceras shui Yii 



Vaginoceras neichianense Yii 



Vaginoceras uniforme Yii 



V aginoceras giganteum Yii 



V aginoceras sp. 



Orthoceras chinense Foord var. eccentrica Yii 



Orthoceras chinense Food var. equiseptatum Yii 



Orthoceras rudum Yii 



Orthoceras suni Yii 



Orthoceras elongatum Yii 



Orthoceras sp. 



Lituites Hi Yii 



4. Northern Hupkh : In northern Hupeh^ the Ordovician deposit is quite 

 similar to that in the western part of Hupeh, comprising the so-called Ichang limestone 

 in the lower part and the Neichiashan formation in the upper. The former attains a 

 thickness of more than one thousand meters while the latter is rather thin in proportion, 

 having only a total thickness of about eighty meters or a little more. The Neichia- 

 shan formation also consists of two parts. The lower part is yellowish green shale 

 about twenty meters thick, and the upper is light greenish argillaceous limestone 

 reaching a thickness of sixty meters or more. It is to be noted that this formation is 

 distributed over a wide area in Hupeh province. As we travelled across these localities 

 namely : Nan-chang, Chung-hsiang, I-cheng, Chingshan and the southern border 

 of Hsiang-yang-hsien, the Neichiashan formation with its striking cephalopod fauna 



I. C. C. Yu and W. P. Shu : Geology of Hsiang-yang, Nan-chang, I-cheng, Ching-men, 

 Chung-hsiang and Ching-shan districts. North Hupeh. Memoir of the Institute of geology, No. VIII 

 National Research Institute of China. 



