152 Bulletin 4 366 



Explanation of Plate 13. 



(33) . 



Page. 



Encliviatoceras ulrichi White 122, 236. 



Lateral view of adult, and two views of a young specimen. 

 (Types). 



NoTS.^^This and the- two following plates are from Bull. 4, 

 U. S. Geological Survey, 



