1919] BASSLER—SPORAXGIOPHORIC LEPIDOPHYTE 81 



may eventually prove to be microsporangia, but until undoubted 

 megasporangia have been discovered we prefer to consider this 

 genus homosporous. Recognizing that practically all known 

 paleozoic Lepidophytes are heterosporous. these must have been 

 preceded in the phylogeny by homosporous forms. 



There appears to be no evidence of a hgule, but it must be 

 recognized that negative evidence concerning an organ as delicate 

 as this, in the case of carbonized impressions such as these under 

 discussion, can have very little value. 



Relation of structure to environment 



The distal attachment of the sporangium by a relatively narrow 

 neck has been looked upon rather generally as archaic or primitive 

 and subject to two obvious disadvantages (33) : (i) such a restricted 

 channel for the passage of food and^ water to the developing spores 

 may lead to nutritional difficulties as the sporangia increase in size; 

 (2) it is mechanically weak. 



The first of these ideas seems to have developed largely with 

 that theory of descent among the Lycopods which holds that 

 Lepidoslrohus, with the linear attachment of its sporangium, is the 

 more highly organized and modern, and Bothrostrobus, with the 

 necklike attachment of its sporangium, the more primitive, for it 

 furnishes one plausible explanation for this modification in descent. 

 The trabeculae and sterile plates which extend upward among the 

 spores in the large sporangia of some of the arborescent Lycopods 

 would add confirmation to this view if they were developed, as 

 Bower (5) and others believe, in response to a demand for yet 

 greater improvement in the mechanism of nutrition. Whether 

 or not the restricted attachment of the sporangium of Canthe- 

 liophorus placed it at a disadvantage in competition with other 

 forms may for the moment be left open. That this attachment 

 is mechanically weak is obvious, but with proper compensation 

 in protecting structures during the period of the development of 

 the sporangium, this very weakness, instead of a disadvantage to 

 the plant, may become a real advantage. In this genus, owing to 

 the weakness of this attachment, the dissemination of the sporangia 

 with their spores must have been very thorough, for the occurrence 



