128 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



EXPLANATION OF THE FIGURES. 



Plate XV. 



All figures of Glyphioceras on this plate are magnified forty times, except fig. 



II, which is four times enlarged. 



Glyphioceras incisuin Hyatt. 



Fig. I. First suture, ananepionic. 



Fig. 2. Second suture, metanepionic (Anarcestes). 



Fig. 3. Third suture, metanepionic. 



Fig. 4. Fourth suture, paranepionic (Tornoceras). 



Fig. 5. Fifth suture, at one-half a revolution, and diameter of 0.74 mm., 

 paranepionic. 



Fig. 6. Eighth suture, at one revolution, and diameter of 0.92 mm., ana- 

 neanic (Prionoceras). 



Fig. 7. Suture at one and three-fourths revolutions, and diameter of 1.29 

 mm., ananeanic 



Fig. 8. Sutures at one and seven-eighths revolutions, and diameter of 1.37 

 mm., (Prionoceras). 



Fig. 9. Sutures at two and one-eighth revolutions, and diameter of 1.64 

 mm., (Prionoceras). 



Fig. 10. Sutures at diameter of 2.25 mm., 2I whorls, transition from 

 Prionoceras to Glyphioceras. 



Fig. II. Sutures at diameter of 15 mm., adult. 



Fig. 12. Sutures of Anarcesles subnautihtius, after L. von Buch, Gesam- 

 melte Werke, Vol. IV, p. 116, PI. XI, fig. 9. 



