PLATE 64. 
ig. 1. 660. 37. Orthoceras undulatum. (Pag. 293.) 
1 a. A fragment of this species on a slab of shale. 
1 b. Another fragment where the laminae are nearly obsolete. 
1 c. A fragment replaced by gypsum, and preserving only the annulations. 
1 d. A fragment near the smaller extremity, showing the laminae but partially preserved. 
1 e. Transverse section of an imperfect and somewhat distorted specimen, showing the position of the 
siphuncle. 
1 /. Yertical section showing the convexity of a septum. 
