224: G. E. Wieland — American Fossil Cycads. 



on the summit are found to persist for a considerable distance 

 downward, and under the microscope are seen to be due to the 

 presence of two ligniiied layers, a single cell in thickness. 

 They correspond to the twelve vertices of soral distribution 

 mentioned above, and their presence is against the idea that 

 the soriferal axis is derived from the fusion of the sporophylls 

 of a male cone like that, for instance, of Zamia integrifolia. 

 Another and much more tenable hypothesis is that the soriferal 

 axis is a series of twelve fused leaves with their sorus bearing 

 pinnules turned inwards. 



While it is evident that the inflorescence under consideration 

 represents a development far in advance of that of existing 

 Cycads, the most striking fact observed is the linear distribu- 

 tion of the sori. This is an archaic character most marked 

 in the Carboniferous ferns, especially the Marattiacece, and 

 their allied forms, living and extinct. 



It has probably been the opinion of all botanists, since it 

 was discovered that Stangeria paradoxa was a Cycad and not 

 a tree fern, as originally described, that the relationship between 

 the Ferns and Cycads must be an exceedingly close one. All 

 later investigations have tended to strengthen this belief. 

 Scott 20 has recently stated that the evidence in favor of the 

 filicinian ancestry of the Cycadew must now be considered 

 overwhelming. 



It was scarcely to be expected, however, that forms bearing 

 strong testimony on this point should display such a marked 

 combination of advanced as well as ancestral characters. 



The further study of the Yale collection promises to afford 

 many new details regarding Cycadean structure and affinity. 

 In addition to the facts presented in this paper, it has been 

 now determined for the first time that the leaf characters of 

 Cycadeoidea were approximately those of Zamia and Die-on, 

 and had the prefoliation of these genera. Moreover, the 

 ancient forms, like the existing Cycads, were dioecious. 



In closing, the writer wishes to express his best thanks to 

 Professors Marsh and Beecher for the indispensable aid he has 

 received during the entire course of the present investigations. 

 He is also indebted to Professor Lester F. Ward for valuable 

 suggestions and reference to important literature. 



Yale Museum, New Haveo, Conn., 

 February 20, 1899. 



