Plate 13 



Page 

 Figures 1-3. MacUiritcH iiitida ( riiich and Scofielcl)? 61 



], 2, Top and uinbilioal views. 



Middle Ordoviciaii. Ssuyen formation: Limestone near 



Niu-lisin-tai, Liao-tnng, Maneburia. 

 3, A polished, vertical section. 

 Middle Ordovician Ssnyen formation : Limestone near 



Miyanobara, Liao-tunji, Manelniria. 

 4,5.13. Orthocirax toyamai. new species «j7 



4, Specimen weathered so as to show the ventral side of 

 the siphuncle. (See also pi. 40, fig. 17.) 



Middle Ordovician, Ssuyen formation : Limestone near 

 Pen-hsi-hu, liiao-tung, Manchuria. 



5, 13, Two polished vertical sections in a lateral direction 

 across the conch, showing the structure of the siphuncle. 



Locality same as Figures 1 and 2. 



0. Orthoccras liaotungense, new species 66 



Specimen weathered so as to show the siphuncle. 

 Locality same as Figure 4. 



7. Sfictoccras- species undetermined 77 



Specimen weathered on its ventral side so as to expose 



the siphuncle. 

 Locality same as Figure 4. 



8,9. Orthoceras species undetermined 08 



Surface view of a cast and section through the conch in 

 a lateral direction, exposing the structure of the 

 siphuncle. 

 Middle Ordovician, Ssuyen formation: Loose block, Niu- 

 hsin-tai, I.,iao-tung, Manchuria. 



10-12. Ci/cloceraa (V) manchuricnae, new species 68 



Dorsal view, showing the nearly transverse annulations; 

 a lateral view of the ventral outline on the right, show- 

 ing the oblique annulati<ms and sutures; and a ventral 

 side cut to expose the structure of the siphuncle. 

 Locality same as Figure 4. 

 120 



