PLATE IX. 



PAGE. 



Orthoceras annulatum J47 



Fig. 1 . View of a fragment of an internal cast, showing the «trength of the anniilations and the dis- 

 tance of the septa. 



Orthoceras crebescens , 148 



Fig. 2. View of a fragment of the species, from Cedarville, Ohio, showing the size of the shell, rate 

 of taper, and arrangement of septa, as well as their curvature and the position of the 

 siphuncle. 



Orthoceras strix 149 



Fig. 3. Lateral view of the specimen described, showing the features of the internal cast. 



