EXPLANATION OF THE FIGURES.* 
PLATE II. 
All figures on this plate are fifteen times enlarged, except Fig. 9, 
which is once and a half its natural size. 
Glyphioceras incisum Hyatv. 
Figs. 1 and 2.—Adolescent stage, one and three fourths whorls, 
diameter of 1.29 mm., last whorl is ananeanic (Prionoceras stage) 
and shows transition from paranepionic. 1, front; 2, side. 
Figs. 3 and 4.—Adolescent stage, diameter of 1.37 mm., one 
and seven eighths whorls, Przonoceras stage. 3, from front; 4, 
from side. 
Figs. 5 and 6.—Adolescent stage, diameter of 1.64 mm., two 
and one eighth whorls, Prionoceras stage. 5, from front; 6, from 
side. 
Figs. 7and 8.—End of adolescent stage, diameter of 2.25 mm., 
two and three fourths whorls; transition from /Prionoceras 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., once and a 
half enlarged. 
* From The Development of Glyphioceras and the Phylogeny of the 
Glyphioceratidez, by J. P. Smith. Proc. Calif. Acad. Sci., third series, vol. 
i, Geology, No. 3, Plate XIV. 
