Plate 25 



Page 



Figure 1. Orfhoccras rcctiscptatuiii. new species 6G 



A polislii'd, vertical section in a lateral direction across the 



conch. 

 Lower Ordovician, Wuting formation : Black limestone near 

 Xiu-hsin-tai, Liao-tun,t,'. Manchuria. 



2. Aniienoccras species undetermined 301 



A polished vertical section in a lateral direction across the 



conch. 

 Lower Ordovician. AVuting formation : Grayish-black lime- 

 .stone near Wu-hu-tsui, Liao-tung, Manchuria. 

 3-5. Xybi/oceras foerstcL Endo 79 



3, A part of siphuncle (X 2) etched by hydrochloric acid, 

 showing the endosiphuncle and septal necks. 



4, A lateral view, with sutures of septa running downward 

 toward dorsal side. (Lower portion of specimen cut out 

 in this figure. ) 



5, Vertical dorsoventral section of the same specimen show- 

 ing location and structure of siphuncle. 



Lower Ordovician, Wuting formation: Black limestone near 

 reu-hsi-hu. Liao-tung, Manchuria. 

 132 



