28 BULLETIN 16 4, UNITED STATES NATIONAL MUSEUM 



Although I have not yet collected any Kangyao or Santao fos- 

 sils in the Tao-yuan-kou section, I have the impression of having 

 seen some fragments of these on the limestone surfaces, and conse- 

 quently it is probable that future field work may develop these 

 formations in this area. 



Niu-HsiN-TAi sixrnoN 



Ordovician strata outcrop extensively all the way around the 

 Niu-hsin-tai coal basin, except on its northwestern sector. The fol- 

 lowing section is a prolongation of the Cambrian and Sinian and 

 was measured on the eastern rim of this structural basin along the 

 line between Hung-lien-kou and Ta-wan-kou. All the strata out- 

 cropping here dip 20° to 30° to the southwest. 



Ordovician 



SSUTEN FORMATION : 



1. Moderately thick-bedded, gray to black limestone with many cal- 

 cite veins, with interbedded thin edgewise conglomerates and dolo- 

 mitic limestones at some horizons; the limestone beds average 7 cm 

 in thickness, 160 m (524.8 feet). 



Fauna. — The contained fossils are found at two horizons from 

 which I collected the following species : 



From upper fossil horizon: 



MacJurites bigshyi (Hall). 

 Cycloceras (?) peitoutsense Grabau. 



From lower fossil horizon: 



Stromatocerium regulatum, new spe- 

 cies. 

 Sactoceras niuhsinense, new species. 



A good many fine specimens, listed on page 14, were found south 

 of Hsiao-nan-kou, on the southern rim of the structural basin. More- 

 over, I have collected a number of black limestone bowlders believed 

 to have come from the Ssuyen formation, in the river drift at the 

 Niu-hsin-tai colliery, in which the following characteristic Ssuyen 

 fossils occur: 



Armenoceras elongatum, new species. 

 Ormoceras orientale, new species. 



Armenoceras sondai, new species. 

 Ormoceras kimurai, new species. 



Orthoceras toyamai, new species. 



Orthoceras sp. 



Cycloceras (?) manchuriense, new 



species. 

 Armenoceras hayasakai, new species. 



Armenoce/'fiw murginale, new species. 

 Armenoceras nanum (Grabau). 

 Armenoceras nudum, new species. 

 Armenoceras yabei, new species. 

 Onnoceras nagaoi, new species. 



2. Moderately thick-bedded, light-gray, dolomitic limestone in 

 layers 1 to 15 cm in thickness, 40 m (131.2 feet). 

 Total Ssuyen formation, 200 m (656 feet). 



