64 



GYMNOSPERMS 



that, from his drawing alone, there is no doubt that the plant is 

 Dioon purpHsii. 



Ccratozamia. — This is a variable genus and several species have 

 been described; but most of them could probably be raised from the 



I'lO. 55. — Dioon spinulosum: on the Hacienda de Joliet, near Tierra Blanca. The 

 plant in the center is about lo meters in height. — After Chamberlain."^ 



seeds of a single cone of Ccralozamia mexicana, the dominant species. 

 C. mexicana is abundant a few miles out from Jalapa in the direction 

 of the extinct volcano, Naolinco (fig. 56). On the precipitous moun- 

 tain side opposite the volcano, growing in dense shade, are hundreds 



