186 THE EVOLUTION OF PLANTS 



an archegonium of Selaginella or Isoetes is re- 

 markably close (see fig. 21, c). Thus we now 

 have full assurance that the process of reproduc- 

 tion hi these Paleozoic Lycopods was the same 

 as in the heterosporous members of the group still 

 living. It is interesting to think that this method 

 has gone on unchanged for such immense ages, 

 and to reflect that in Selaginella and Isoetes we 

 have, from this point of view, plants of the 

 Palaeozoic Flora still flourishing. 



The Lycopods, however, have long passed their 

 best days; then* most advanced representatives 

 flourished in the Carboniferous epoch, and, so 

 far as we know, have left no descendants. We 

 have already considered one of the "seed-bear- 

 ing Club-mosses" the little herbaceous plant 

 Miadesmia. The same high grade of reproduc- 

 tion was attained by some of the tree-Lycopods, 

 in which, indeed, the seed-like organs were first 

 discovered. The genus is known by the name 

 of Lepidocarpon, and is based solely on the seed- 

 character, for in all other respects the structure 

 of the cone is exactly like that of a Lepidoden- 

 dron. The seeds were known for many years 

 before they were proved to belong to a Lycopod, 

 and were then supposed to be Gymnospermous 

 seeds of the family Cordaiteae. 



In the young condition the arrangement of 

 the parts of the cone is precisely the same as in 



