Vol. I. C. C. Yu — Ordovician Cephalopoda of Central China (n) 9 



lower part, and Ichang limestone as well as Neichiashan Series at the Upper, the 

 former one denoting the Cambrian deposit and the latter two the Ordovician. The I- 

 chang limestone attains a thickness of from 1250 m. to 1680 m. and yields fossils of 

 Lower Ordovician age such as Callograptus cf salteri Hall, Proterocameroceras mathieui 

 Grabau, Eccyliopterus. sp., Asaphus sp. ArchiKocyathus chiliensis Grabau, Girvanella 

 sinensis Yabe etc. The Ichang limestone is again disconformably overlaid by the Nei- 

 chiashan Series, no m. thick, which consists of two parts. The lower part is an 

 alternation of green, calcareous shales and brownish yellow or light gray limestone 

 characterized by Triplecia (Yangtzeella) poloi (Martelli) Kolarova, and Clitamhonites 

 giraldii Martelli; and the upper one is a dense gray limestone crowded with abundant 

 Orthoceras. This series has furnished besides Triplecia {Yangtzeella) poloi Martelli, and 

 Clitambonites giraldii Martelli, the following: Orthis calligramma Dalm., Eccyliopterus 

 sinensis Freeh, Vaginoceras duplex Wahlenberg, Discoceras eurasiaticum Freeh, Endo- 

 ceras sp., Cycloceras sp., Cyrtoceras sp., Asaphus cf expansus Dalm., and many 

 specimens of Orthoceras. A preliminary determination of the cephalopods in this 

 collection was made by Prof. Grabau, but some are missing from the Geological Museum 

 of Peking University except the specimens of Orthoceras chinense Foord, Discoceras 

 eurasiaticum Freeh and the so-called Cyrtoceras which now is known as Meloceras 

 asiaticum Yabe. During the autumn of 1924 Messrs. C. Y. Hsieh and Y. T. Chao again 

 carried on field work in the western part of Hupeh' and collected one species of 

 cephalopod from tlie Ichang limestone and a lot of them mainly from the upper part of 

 the Neichiashan formation at the places near Lo-jo-ping and Chien-yang-ping. Prof. 

 Grabau asked me to make a thorough study of these cephalopods of which he has made 

 a preliminary examination. The material includes the following species: 



a. From Ichang limestone 



Cameroceras cf. styliforme Grabau 



b. From Neichiashan formation (upper part) 



Cameroceras tenuiseptum Hall var. ellipticum Yii 



Cameroceras hsiehi Yii 



Cameroceras subtile Yii 



Cameroceras sp. 



V aginoceras neichianense Yii 



V aginoceras reedt Yii 



V aginoceras multiplectoseptatum Yii 



I. C. Y. Hsieh and Y. T. Chao: Geology cf I-chang, Hsing-shan, Tze-kuei and Pa-tung dis- 

 tricts, W. Hupeh. Bulletin of the Geological Survey of China. No, 7. 



