PLATE XIX. 



FAGB. 



"Fig. 1-3- Physoxemus Altonessis. St. J. and W 454 



1 a. Side view of large specimen : I 6, front view. 1 c, view of the posterior face <■; ld,e,f,g, 



transverse sections at points indicated by corresponding letters, fig. 1 a. St. Lonis 

 limestone; Alton, Illinois. 



2 a. Side view of a smaller spine, the posterior face broken away, restored in outline; 2 6, 



c, d e,/, transverse sections. Same horizon and locality. 



3 a. Side view of very small spine, probably referable to the above species, but having the 



anteroinferior shoulder truncated; 3 6, front view ; 3 c, d, e, transverse sections. 



St. Louis beds ; Pella, Iowa. 



Fig I Phtsonkmus Chesterexsis, St. J. and "W -155 



A a. Side view enlarged two diameters, and outline natural size: 4 6, front view, enlarged 



two diameters: 4 c, d, e, transverse sections, enlarged two diameters.- Chester 



limestone; Chester, Illinois. 

 Fig. 5, f>. Drepanacanihus reversus, St. J. and W 156 



5 a. Side view of fragment of spine, base restored in outline, anterior limit of internal 



cavity indicated by the dotted line: 5 6, enlargement, showing tubercnlation of 

 the anterior border; 5 c, enlargement of tubercles of middle ridge; 5 d, enlarge- 

 ment of tubercles posterior ridge; o e, transverse section, posterior face rostored in 

 outline. St. Louis limestone : Alton, Illinois. 



6 a. Lateral view of small, worn spine, possibly referable to the above species, and trans- 



verse section of the same. Same horizon, St Louis, Missouri. 



