PLATE XVII. 



Chonophyllum Canadense, Billings (page 185). 



Figure 1. Type specimen, as seen from above, showing the calyx and the horizontal 

 frill-like extension surrounding it ; from South-west Point, Anti- 

 costi. One half the natural size. 



Figure la. Side view of the same ; one half the natural size. 



Figure 16. The raised concentric markings of the upper surface. 



Figure lc. Diagrammatic section of the type specimen ; one half the natural size. 



Figure 2. Longitudinal section through the calyx of a young individual from South- 

 west Point, Anticosti. 



Figure 3. Longitudinal section through the calyx of a larger specimen from the same 

 place 



Figure 3a. Part of the same section, enlarged twice, to show the structure. 



Figure 36. Transverse section of the specimen, represented in figure 3, through the vis- 

 ceral chamber a little above the base. 



Figure 4. Vertical tangential section, showing the superimposed layers of two septal 

 ridges, ahout midway between the raised calicular area and the 

 edge of the lateral extension ; from another specimen from South- 

 west Point, Anticosti. Twice the natural size. 



