450 



GENERA INCERTAE SEDIS 



[CH. 



rocks in Tonkin 1 where Podozamites also occurs. Heer 2 in his 

 account of some impressions of Podozamites from Spitzbergen 

 figured a seed in close association with what he believed to be a 

 carpellary leaf like that of a Cycad and suggested a connexion 

 between the seed and Podozamites: this supposed connexion has, 

 however, little to support it. 



FIG. 812. A, B, Cycadocarpidium Erdmanni. A, Restoration of fertile shoot. 

 B, Single sporophyll with seeds. C, D, Cycadocarpidium Swabii. (After 

 Nathorst.) ' E, Podozamites distans. Epidermal cells. (After Schenk.) 



Nathorst's view of the sporophylls is that each is a single fertile 

 leaf bearing two ovules comparable morphologically with the 

 megasporophylls of Dioon, but, as he points out, the terminal 

 portion of the sporophyll of Cycadocarpidium is much more leaf- 

 like than the sterile distal end of the megasporophylls of Dioon, 

 Encepkalartos Zamia. He considers that the evidence afforded 



1 Nathorst (II 4 ) p. 5. - Heer (77) i. PI. vm. fig. 4. 



