SPORE-PRODUCING MEMBERS 



321 



details in them restricts the comparison to the basis of mature structure. 

 On this footing it appears that the type of sporangium characteristic of 

 the sub-genus Urastachya, and showing special resemblance to that of 

 Lycopodium Phlegmaria, dates back at least to the calciferous sandstone, 

 for it is seen in Lycopodites Stockii (compare Fig. 147). Sporangia apparently 

 of the same type have been recognised also in other early fossils referred 

 to Lycopodites, but their small size and the state of preservation do not 



Spoiceritcs insignis. Somewhat diagrammatic radial section of part of the cone, 

 showing two sporophylls in connection with the axis. On the lower sporophyll the 

 sporangium is shown attached at its distal end to the ventral outgrowth of the sporophyll : 

 within the sporangium some of the characteristic winged spores are shown. (After Miss 

 Berridge.) From Scott, Progressus rei Botanicae, vol. i. 



allow of any exact comparison. Of other apparently non-ligulate types one 

 of the best known as regards the details of the strobilus, though its vegetative 

 region is still unknown, is Spencerites (Fig. 167), which has been described 

 by Scott and others from specimens showing microscopic structure. Here 

 the verticillate or spiral sporophylls consist of a narrow pedicel bearing an 

 upturned lamina ; at the base of the lamina is a massive ventral outgrowth, 

 to which the distal end of the sporangium is attached by a narrow neck. 

 The presence of the ventral sporangiferous lobe has suggested to Dr. Scott 

 a comparison with the Sphenophyllales, though the absence of any vascular 

 supply to the " ventral lobe " renders the analogy somewhat remote. It 



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