PLATE XII. 



HOLOCrSTITES SCVTELLATUS, HaLL. 

 Page 357. 



Fie. 1. Lateral view of the specimen described. The plates on the left side are obscured by- 

 adhering rock. 



HOLOCYSTITES OVATUS, HaLL. 

 Page 357. 



Fig. 2. Lateral view of a specimen of this species. 



HOLOCTSTITES WINCHELLI, HaLL. 

 Page 356. 



Fi&. 3. A view of the specimen described, which is imperfect at the base and summit. 



HOLOCYSTITES CTLINDRICUS, HALL. 

 Page 354. 



Fig. 4. A view of a well preserved individual of large size, on wliioh the limits of the plates 

 are strongly marked. 

 " 5. View of a smaller individual. 



" 6. View of a small specimen (preserving a portion of the short column), on which the 

 angular prominences of the plates and the surface pustules are well preserved. 



HOLOCYSTITES ABNORMIS, HaLL. 

 Page 355. 



Fig. 7. Lateral view ol -a cast of a large specimen, which preserves the limits of the plates and 

 the minutely pustulose texture of the surface. 

 " 8. View of a smaller specimen. The peculiar arrangement of the plates in the lower part 

 of the body is seen in both this and the preceding specimen. 



HOLOCYSTITES ALTERNATUS, HaLL. 

 Page 355. 



Fig. 9. View of a very distinctly marked specimen of this species, showing the position of the 

 summit aperture and the arrangement of the plates of the body. 



ECHINOCYSTITES jyODOSUS, HaLL. 

 Page 360. 



Figs. 10, 11. Lateral and summit views of the specimen described. 



Afiocystites imago, Hall. 



Page 358. 



Fig. 12. Lateral view of the specimen, showing the structure of the body and the position of the 

 openings. 



Hemicosmites subolobosus. Hall. 



Page 359. 

 Fig. 13. View of a specimen which shows the structure of the body. 



