Plate 22 



Page 



Figure 1. Ormoceras species undetermined 107 



Specimen weathered on its ventral side exposing the si- 



pliuncle. 

 Middle Ordovician, Ssuyen formation : Limestone near Wu- 

 hu-tsui, Liao-tung, Manchuria. 



2. Ormoceras species undetermined 107 



A polished vertical section in a lateral direction across the 



conch, showing the structure of the siphuncle. 

 Locality same as Figure 1. 



3. Ormoceras species undetermined 107 



Specimen weathered en its ventral side exposing the si- 

 phuncle. 



Middle Ordovician, Ssuyen formation: Near Miyanohara 

 Station, Liao-tung, Manchuria. 



4. Gonioceras species undetermined 109 



A polished vertical section in a lateral direction across the 



conch, showing the structure of the siphuncle. 

 Middle Ordoviciiui, Ssuyen formation: Near Pen-hsi-liu, 



Liao-tung, Manchuria. 



5, 6. Armenoceras iassleri, new species ^2 



6, A natural vertical section in a lateral direction somewhat 



obliquely across the conch. 

 5, A polished vertical section of same specimen across the 



conch, showing the structure of the siphuncle. (See also 



pi. 40, fig. 12.) 

 Middle Ordovician, Ssuyen formation: Near Hsia-kang-yao, 



Liao-tung, Manchuria. 



7. Ormoceras taitsuense, new species 107 



A polished vertical section in a lateral direction across the 

 conch, showing the structure of the siphuncle. (See also 

 pi. 40, fig. 4.) 



Middle Ordovician, Ssuyen formation: Limestone block, 

 Niu-hsin-tai, Liao-tung, Manchuria. 



8. Ormoceras tail, new species 106 



A polished vertical section in a lateral direction across the 

 conch, showing the structure of the siphuncle. (See also 

 pi. 40, fig. 10.) 



Middle Ordovician, Ssuyen formation: Black banded lime- 

 stone near Niu-hsin-tai, Liao-tung, Manchuria. 



9. Ormoceras species undetermined 108 



A partly polished vertical section in a lateral direction 



across the conch. 

 Formation and locality same as Figure 4. 



10. Isoteloides species undetermined 112 



Dorsal view of the single pygidium found. 

 Formation and locality same as Figure 4. 



11-] 3. Dalmanella (?) species undetermined 44 



Three partly exfoliated pedicle valves. 



Lower Ordovician, Wuting formation: In gray banded lime- 

 stone near Pen-hsi-hu, Liao-tung, Manchuria. 



129 



