8 BULLETIN 164, UNITED STATES NATIONAL MUSEUM 



A. Grey colored limestone with Cryptozoon sometimes intraformational 



conglomerate layers are found in the upper part 50-60 m. 



B. Alterations of greyish white crystalline limestone and black 



marl 50-60 m. 



C. Grey banded limestone sometimes intercalating intraformational con- 



glomerate layers 40-50 m. 



D. Tofango fossil bed. Dark limestone, sometimes dolomitic, with many 



brown colored nodular masses 50-^0 m. 



E. Grey compact dolomitic limestone containing flinty nodules in the 



lower part 140-180 m. 



In more recent years, O. Aoji, formerly a member of the Geological 

 Institute of the South Manchuria Railway Co., studied the Manchu- 

 rian geology in considerable detail, and in 1927, in the explanatory 

 text accompan3dng his geological map of Feng-huang-cheng, sum- 

 marized the Ordovician strata occurring in the Tai-tzu district. The 

 order of succession recognized by him is as follows, in descending 

 order : 



Black or grey limestone 75-120 m. 



Maclurea 



Actinoceras 

 Greyish black limestone, with some nodules of hornstone-like sub- 

 stances 12-75 m. 



Maclurea 



Piloceras 



Calymene 

 Kumogata limestone with edgewise conglomerate 20-30 m. 



Brachiopoda 



Maclurea 



Actinoceras 



Greyish white crystalline limestone 25-50 m. 



Greatest Uzumaki limestone 10-25 m. 



Actinoceras 



In the same year, K. Ozaki, of the Tohoku Imperial University, 

 published the results of many years' field work in the Ordovician 

 of the Yen-tai and portions of the Tai-tzu-ho districts. His columnar 

 section is as follows, in descending order : 



Upper grey limestone zone. 



Grey limestone zone, containing some nodules. 

 Maclurea limestone zone. 



Maclurea 



Piloceras 



Manchuriocoras new genus 



ActinocG7-a8 

 Lower grey limestone, intercalating wide edgewise conglomerates. 

 Crystalline limestone zone. 

 Edgewise conglomerate zone. 

 Uzumaki limestone zone. 



