Plate 15 



Page 

 FiGUBES 1-3. Armcnoceras clcgans, new species 84 



1, A lateral view of the siphuncle. Upper part of specimen 

 cut vertically through the center of the siphuncle to show 

 its structure. 



2, A natural, vertical section in a lateral direction across 

 the couch, showing the structure of the siphuncle. 



Middle Ordovician, Ssuyen formation : Limestone near Pen- 

 hsi-hu, Liao-tung, Manchuria. 



3, A weathered natural section of the siphuncle. 



Middle Ordovician, Ssuyen formation : Near Niu-hsin-tai, 

 Liao-tuug, Manchuria. 

 122 



