BRACHIODODA FROM THE ORTHIS BED OF THE 

 NEICHIA FORMATION OF CENTRAL CHINA* 



By M. 8. Chang 



INTRODUCTION 



The material described in tliis paper was collected by Mr. C. C. Yii, geo- 

 logist to the Institute of Geology, National Research Institute, at Taihungshan, 

 Nanchang Hsien, Hupeh (.imt\^iM-m-i:&\h) in 1928. When the writer joined 

 the Geological Survey last February it was kindly put into his hands for study 

 at the suggestion of Professor Grabau. To Mr. Yii he, therefore, wishes to ex- 

 press his sincere thanks. To Professor Grabau under whose sympathetic and in- 

 spiring guidance the study was made, he is also greatly indebted. 



Stratigraphy of the Neichia Formation. 



In his illuminating study of the geology of the Yangtze Gorges Professor 

 J. S. Lee first established the Neichiashan Series, now designated the Neichia 

 Formation. It was subdivided into two parts, an upper, the Pagoda Limestone 

 and a lower, the Triplecia Beds (Now Yangtzeella Beds). The Pagoda Lime- 

 stone is a dense gray rock, only a few meters thick and characterized by the 

 gigantic Orthoceras chinense Foord. The Triplecia (Yangtzeella) Beds, on the other 

 hand, consist of an alternation of a dirty green, calcareous shale and slabby brown- 

 ish-yellow or light grey limestones of a rather earthy composition with a thin- 

 bedded gL-ey limestone at the base. The slabby limestones are everywhere crowd- 

 ed with Triplecia (Yangtzeella) jjoloi and Clitamhonites giraldil. In the list of 

 fossils Professor Lee gave the following species: 



Triplecia (Yangtzeella) poloi Martelli (very abundant) 

 Clitamhonites giraldii Martelli ( ,, ,, ) 



Orthis calligramma Dalman ( not rare ) 



Eccyliopteris sinensis Freeh (abundant) 



Vaginoceras duplex Wahlenb. ( ,, ) 



* Received for publication in 193 1. 



