PLATE XXV. 



Page. 



GLYMMATACANTHUS BUDIF, St. and W 249 



Fig. la. View of fragment of spine from the right side, outline partially restored; 



1 6, do., from the anterior border; 1 c, do., transverse section; Keokuk; 

 Keokuk, Iowa. Mr. Cox. 



GLYMMATACANTHUS PETRODOIDES, St. J. and W 250 



Fig. 2 a. View of fragment of spine, showing part of lateral surface tuberculation; 



2 b, do., restored outline of transverse section; 2 c, do., enlargement, 

 showing radiately-soulptured tubercles, as seen in profile. Chester; 

 Chester, Illinois. Dr. Hambach. 



OKACANTHUS BECTUS, St. J. and W 257 



Fig. 3 a. View of fragment of spine, showing portion of the posteriori?) border; 3 b, 

 do., from the right (?) side; 3 c, do., in transverse section, restored. 

 Chester; Chester, Illinois. Dr. Hambach. 



BATACANTHUS ? NECIS, St. J. and W 253 



Fig. 4 a. View of spine from the left side, base restored in outline; 4 b, do., transverse 

 sections near tip and at middle, the latter crushed in over the pulp 

 cavity, with a restored section. Keokuk; Keokuk, Iowa. Mr. Cox. 



