4o8 



MORPHOLOGY OF GYMNOSPERMS 



VSOOmi. 



/000m, 



460 



Figs. 459, 460. — Diagrams indicating the historical con- 

 nections of the gymnosperm groups and the relative periods of 

 time involved: fig. 459, a sector of the earth, showing to scale 

 the thickness of the superficial deposits (shaded) from which 

 fossil records have been obtained; fig. 460, the suggested 

 historical connections of the gymnosperm groups, all contained 

 within the shaded region of fig. 459. — Prepared by Sister 

 Helen Angela. 



459 



