Plate 3 



I'age 



Figure 1. Armcnoceras hcirioi (Kobayashi) 87 



A partly polished vertical section in a lateral direction across 



the conch exposing the structure of the siphuucle. 

 Middle Ordovician, Ssuyen formation : Limestone near 

 Miyanohara, Liao-tung, Manchuria. 



2-6. Armenoceras asiaticum, new species 81 



2. A weathered natural, vertical section in a lateral direc- 

 tion across the conch, exposing the structure of the 

 siphuncle. 

 Middle Ordovician, Ssuyen formation : Limestone near Pen- 



hsi-hu, Liao-tung, Manchuria. 

 3-5, Three polished, vertical sections in a lateral direction 

 across the conch, showing the structure of the siphuncles. 



6, A transverse section of the same specimen as Figure 5 

 across the upper part, showing the relative size and 

 location of the siphuncle. 



Middle Ordovician, Ssuyen formation : Limestone near Pen- 

 hsi-hu, Liao-tung, Manchuria. 

 7, 8. Armenoceras nanum takayamai, new variety 93 



7, A polished, vertical section in a somewhat oblique lateral 

 direction across the conch, showing the structure of the 

 siphuncle in its lower part. 



Middle Ordovician, Ssuyen formation : Limestone near Wu- 

 hu-tsui, Liao-tung, Manchuria. 



8, A polished, vertical section in a lateral direction across 

 the conch, exposing the structure of the siphuncle. 



Middle Ordovician, Ssuyen formation : Limestone near Pen- 



hsi-hu, Liao-tung, Manchuria. 



9. Armenoceras orientale, new species 80 



Specimen with living chamber, weathered on the ventral side 



(see also pi. 40, fig. 14) exposing the siphuncle. X V2- 

 Middle Ordovician, Ssuyen formation : Limestone near Yen- 



tai, Liao-tung, Manchuria. 



10. Actinoceras concavum, new species 78 



A polished, vertical section in a lateral direction across the 

 conch, showing the structure of the siphuncle. 



Middle Ordovician, Ssuyen formation : Loose block near Pen- 

 hsi-hu, Liao-tung, Manchuria. 



11. Ormoceras species undetermined 107 



A polished vertical section of the same specimen as Plate 14, 

 Figure 5, in a lateral direction across the conch, showing 

 the structure of the siphuncle. 



123 



