FLORA OF THE CARBONIFEROUS EPOCH. 53 



scale; and it agrees with Lepidostrobus in the sporangia 

 containing only small spores (woodcut 44, 10). 



^' In comparing these fossils with the living club-mosses, one 

 is struck with the singular agreement in the organisation of 

 plants so far removed in time, and so different in size, as the 

 recent humble club-mosses and the palaeozoic tree Lepidoden- 

 drons. The fruit of Triplosporites, like that of Selaginella 

 (woodcut 44, 1), contains large and small spores, the micro- 

 spores being found in both genera on the middle and upper 

 scales of the cone, and the macrospores on those of the 

 lower portion (Fig. 43). 



" On the other hand, the fruits of Lepidostrobus and 

 Flemingites agree with that of Lycopodiiim in having only 

 microsj)ores. The size of the two kinds of spores also singu- 

 larly agrees in the t^vo groups. This is of some importance, 

 for among the recent vascular Cryptogams there is a remark- 

 able uniformity in the size of the spores in the members 

 of the different groups, even when there is a great variety in 

 the size of the plants. Thus the spore of our humble wall- 

 rue is as large as that of the giant Alsophila of tropical 

 regions. So also the spores of Equisetum and Calamites 

 agree in size, as may be seen in woodcut 47, Figs. 3, 4, and 9, 

 where the spores of the two genera are magnified to the same 

 extent. And a similar comparison of the macrospore and 

 microspore of Triplosporites with those of Selaginella, and of 

 the microspore of Lepidostrobus with that of Lycopodium, 

 exhibits a similar agreement. .This is made apparent by 

 the drawings in woodcut 44 of the two kinds of spores of 

 Selaginella, 3 and 4, with those of Triplosporites, 8 and 9, 

 which are drawn to the same scale." 



The genus Sigillaria, as we have already said, has, according 

 to the observation of Hooker, small sporangia exactly agreeing 

 in size and form with those of Flemingites. Most probably 

 the contents of these small sporangia were the same in both 

 genera, so that Sigillaria W' ould be placed with Flemingites 



