PLATE LXIII. 



Tage. 

 Fig. 1. Plalyceras primordialis 453 



1. Cast of interior of shell. 



Fig. 2. Hyolithes primordialis 454 



2. View of flat side and two sections of a large specimen. 



2a. Reproduction of photograph of a slab of sandstone, with numerous specimens of 

 S. primordialis, from the St. Croix sandstone of Wisconsin. Tho small shells are 

 identical with R. gregaria of M. and H. 

 Fig. 3. Agnostus interstrictus - 454 



3. Entire specimen, from Antelope Springs, Utah. 

 3a. Pygidium, from Gallatin Range, x 6. 



Fig. 4. Agnostus bidens 455 



4. Cephalic shield, x 6. 

 4a. Pygidiuiii. x 6. 



Fig. 5. Agnostus tumidosus -- 455 



5. Cephalic shield, x 6. 



5a. Pygidium, associated with fig. 5. x 6. 

 Fig. 6. Haguia sphairica 442 



6. Reproduction of photograph of thin section, x 8. 



6a. Drawing of thin section, x 9. The light-colored spaces are the fillings of the canals. 

 They correspond to the darker spaces of the photograph. 



474 



