Plate XXII — Continued. 



PAGE. 



Fig 12 Gampsacaktiius typus, St J and "W 472 



12 a. Side view of a nearly entire spine of medium size, enlarged two diameters, snow- 

 ing spiinisi- processes at the apex, base partially restored from specimens in the 

 collection of ilr Vail Home and Prof. "VVorthen. 12 b, enlargement of a section 

 near the middle of the spine, Showing lateral .surface and either border; 12 c, 

 transverse section near base, enlarged two diameters, and, 12 d, probable outline 

 of the same when pi i feet. St. Louis limestone; St. Louis, Hissouii. 

 Fig. 13. Gampsacaxthus sqi"amosus, St. J. and W 473 



Via. Side view of fragment . -bowing upper portion of spine, enlarged one-half: 13 6, en- 

 largement showing form and disposition of tubercles; 13 c, transverse sections 

 near lip and across the broken base, enlarged one-half. St. Louis limestone; St. 

 Louis. .Missouri. 



Gampsacanthus ? latus, St. J. and W 474 



Side view of tip of spine, enlarged one-half; 11 6, enlargement of portion of lateral 

 surface; 14 c, transverse section. Keokuk limestone ; Boonville. Missouri. 



Okacantiius coxsimtlis, St. J. and W 478 



Side view of a fragment apparently from near the miildle of the spine; 15 b, sketch 

 of the concave margin, showing form and arrangement of tubercles ; 15 c, sketch 

 showing convex border: 15 d, transverse section, distorted by pressure. St 

 Louis limestone ; Alton, Illinois. 



Fig. 16. Oil acanthus ? obuquus, St. J. and W .477 



16 a View of the anterior (?) margin of a fragment of the upper portion of a spine j 16 b,c, 



transverse section. Keokuk limestone : "Warsaw, Illinois. 



Fig- 



14 







14 



a 



Fis 



15. 







15 



a 



