EXPLANATIONS OF PLATE 18 (9). 



GoMPHOCERAS SCRINTUM vel MARCY^. page 850 (46). 



Fig. 1. Lateral view of the outer chamber, the lower end showing the concavity of the 



septa. 

 " 2. View of the aperture, of the same individuaL 

 " 3. A transverse section of another individual, showing the size and position of the 



siphuncle, with muscular or vascular markings at the margin. 



Cyrtoceras laterals. page 357. 



Fig. 4. Dorsal view of a specimen, showing septa and preserving the remains of faint 



longitudinal ridges. 

 " 5. Lateral view of the same individual. 

 " 6. The outer circle of the figure represents the form of section and the position of 



the siphuncle of this species, the inner portion that of C. lucillum. 



Cyrtoceras lucillum. page 349 (45). 



Fig. 7. Lateral view of a specimen of this species. The figure is somewhat restored. 

 See inner portion of figure 6 for transverse section. 



Cyrtoceras beevicorne. page 356. 



Figs. 8, 9. Lateral and dorsal views of the specimen described. The specimen consists 

 of the filling of the outer chamber and the matrix of the lower part, which 

 has been represented from a cast in the cavity. 



Orthoceras abnorme. page 355. 



Fig. 10. View of a specimen of this species having the filling of the chambers in the 

 lower part broken away, showing the siphuncle, and the inner core with its 

 numerous ramifications uniting with the walls of the siphuncle. The view 

 is taken looking obliquely upon the specimen, so that the real amount of 

 curvature is not observable. 



