126 CALIFORNIA ACADEMY OF SCIENCES. [Proc. sdSek. 



EXPLANATION OF THE FIGURES. 



Plate XIV. 



All figures on this plate are twenty times enlarged, except fig. 9, which is 



twice natural size. 



Glyphioceras incisum Hyatt. 



Figs. I, 2. Adolescent stage, one and three-fourths whorls, diameter of 

 1.29 mm., last whorl is ananeanic (Frionoceras stage) and shows transition 

 from paranepionic. i, front; 2, side. 



Figs. 3, 4. Adolescent stage, diameter of 1.37 mm., one and seven-eighths 

 whorls, Frionoceras stage. 3, from front; 4, from side. 



Figs. 5, 6. Adolescent stage, diameter of 1.64 mm., two and one-eighth 

 whorls, Frionoceras stage. 5, from front; 6, from side. 



Figs. 7, 8. End of adolescent stage, diameter of 2.25 mm.; two and three- 

 fourths whorls; transition from Frionoceras to Glyphioceras in the division 

 of the ventral lobe, and beginning rounding of the whorl. 7, side view; 

 8, front view. 



Fig. 9. Early adult stage, diameter of 15 mm., twice enlarged. 



