EXPLANATIONS OF PLATE 12 (3). 



HoLOCYSTiTES scuTELLATUs. page 314 (10). 



Fi-^. 1. Lateval view of the specimen described. The plates on the left sido are obscured 

 by adhering rock. 



HOLOCYSTITES OVATUS. page 313 (9). 



Fi?. 2. Lateral view of a specimen of this species. 



HoLOCYSTiTES wiNCHELLi. page 313 (9). 



Fig. 3. A view of the specimen described; which is imperfect at base and summit. 



HoLOCYSTiTES CYLiNDRicus. page 311 (7). 



Fig. 4. A view of a well preserved individual of large size, on which 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 promiuences of the plates and the surface pustules are 



well preserved. 



HOLOCYSTITES ABNORMIS. page 312 (8). 



Fig. 7. Lateral view of 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. page 3l2 (8). 



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 NODOSus. page 316 (12). 



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



Apiocystites imago. page 314 (10.) 



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

 position of the openings. 



Hemiscosmites subglobosus. page 316 (12). 



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



GoMPHOCYSTiTES GLANs. page 310 (6). 



Fig. 14. Lateral view of a cast of a specimen, which shows the general form, the posi- 

 tion of the central opening, grooves ol the spiral appendages of the dome, 

 and impressions of some of the plates of the dome and body. 



GoMPiiocYSTiTEs TENAx. page 310 (6). 



Fig. 15. Enlarged view of a specimen from Lockport, N. Y., which preserves the plates 

 of the upper part of the body and dome, showing their spiral arrangement 

 and nodose character. 



