30 BULLETIN 164, UNITED STATES NATIONAL MUSEUM 



2. Moderately thick-bedded, light-gray, buff-weathering arena- 

 ceous dolomitic limestone, and beds averaging 7 cm in thickness, 80 m 

 (262.4 feet). 



Total thickness of the Ssuyen, 100 m (328 feet). 



WUTING FORMATION : 



Moderately thick-bedded gray to black limestone with a few edge- 

 wise conglomerate and some arenaceous limestones. The limestone 

 beds vary in thickness from 2 to 20 cm, 200 m (656 feet). 



Fauna. — Although I have not collected any Wuting fossils in this 

 immediate section, I found a specimen of Raf-nesquina sp. near 

 Hsiao-shih. In my rapid reconnaissance, nothing was seen of the 

 Kangyao and Santao formations, but they are probably present ; this 

 can be settled, however, only by future field work. 



COMMENTS ON THE GEOGRAPHIC DISTRIBUTION OF 

 THE ORDOVICIAN 



The distribution of the Canadian and Ordovician formations in 

 the Kuantung, Pechili, and Tai-tzu-ho districts, described in the 

 preceding pages, is shown graphically in the accompanying chart 

 (p. 31). Several significant facts are apparent from a brief perusal 

 of it. In the first place the Canadian Santao formation is lacking 

 in the Kuantung and Pechili districts, at least so far as a fairly 

 careful survey indicates. On the other hand, the Kangyao may 

 have a wider distribution than my own collecting indicates, for 

 while I found no characteristic fossils nor beds with the typical 

 lithology, except in the Hsia-kang-yao and Wu-hu-tsui sections, T. 

 Kobayashi reports the following species from three other areas : 



From near Pen-hsi-hu : 



Lophoapira trochifomiis Grabau. I Pagodispira deruiduii Grabau. 



Lophospira gerardi Grabau. | 



From near Niu-hsin-tai : 



Lophospira acuta, Grabau. 

 Lophospira trochiformis Grabau. , 



From Wu-hu-tsui (Actinoceras zone) : 



Lophospira morrisi Grabau. Pagodispira denoiduii Grabau. 



Lophospira gerardi Grabau. 



These fossils belong to Kobayashi 's Toufangkou fauna, which he 

 correlates with Grabau's Machiakou limestone and which both of 

 these authors consider typical North American Black River fauna. 

 Even though only one species is common to Kobayashi's Toufangkou 

 and my Kangyao faunas, it is apparent from a brief study that the 

 Kangyao is to be regarded as equivalent to the lower part of Kob- 

 ayashi's Toufangkou formation. It is reasonable, therefore, to 



Lophospira morrisi Grabau. 



