LEPIDOSTROBUS 181 



the attachment is extremely narrow tangentially, so 

 that a radial section of the cone seldom follows the 

 plane of insertion for more than a small part of its 

 length. Hence the connection between the two organs 

 has sometimes been represented as much less extensive 

 than is actually the case. The pedicel is grooved 

 along its upper surface, and into this groove the narrow 

 band of tissue fits, by which the sporangium and 

 sporophyll are connected. The large baggy sporangium 

 projects on either side considerably beyond the limits 

 of the pedicel. 



The wall of the sporangium, as preserved, consists 

 of a single layer of prismatic palisade-like cells, very 

 characteristic of Lepidostrobus sporangia, though in 

 some species the wall has a more complicated structure. 

 Along the lower side of the sporangium, where it 

 is attached to the sporophyll, a pad of delicate tissue 

 rises into its cavity, and spreads laterally for some 

 distance along the interior of the wall. In other forms 

 this internal tissue is more developed, and may even 

 be prolonged into trabeculae, comparable to some 

 extent with those of Isoetes. It has been suggested by 

 Bower, 1 that these extensions of the sterile tissue into 

 the cavity of the sporangium may have served to 

 facilitate the nutrition of the developing spores, and 

 may also have contributed to the mechanical support 

 of the sporangial wall. Both points may well have 

 been of importance in spore-sacs of such large size, with 

 so slender an attachment to the subtending leaf. 



In Lepidostrobus oldhamius and some other forms, 



1 "Studies in the Morphology of Spore-producing Members," Part i., 

 Phil. Trans. B, 1894. 



