1888.] 



481 



[Newell. 



the greater curvature, more rapid expansion of the shell and greater 

 breadth of living chamber near the aperture. 



H. Hertzerii H. & W. is flattened in the region of the ventral 

 opening, and the dorsal aperture is not so clearly developed into 

 distinct lobes. 



Locality. — Delphi, Ind. 



Hexameroceras cacabiformis n. sp. 



Ventral view 

 Lateral view. 



Aperture. 



Shell of medium size, straight ; transverse section subcircular ;. 

 closed chambers and test unknown. 



The living chamber is short, its height along the vertical axis be- 

 ing a little less than three-fourths the greatest diameter. On the 

 edges of the last septum are crenulations. (In the figures above, 

 these are somewhat too small and regular.) The shell increases but 

 slightly in diameter above the base of the living chamber excepting 

 on the ventral side where it swells out below the ventral aperture. 

 The greatest dorsi-ventral and lateral diameters are on a plane 



PROCEEDINGS B. S. N. H. VOL. XXIII. 31 JUNE, 1888. 



