Seed-Plants 131 



ment during the Carboniferous. Recent studies of 

 these Carboniferous " ferns " show that many of 

 them were really intermediate in character between 

 the true ferns and the cycads, and many of them 

 produced true seeds, hence the very proper name of 

 Pteridosperms, or seed- ferns, applied to these. It 

 is highly probable that from some of the pterido- 

 sperms the cycads are directly descended, and per- 

 haps also the curious Ginkgo, which has been re- 

 ferred to, whose sole representative now flourishes 

 in the temple gardens of China and Japan, and 

 occasionally is seen in our parks and gardens. The 

 great variety of these seed-bearing ferns indicates 

 that the seed habit was developed in more than one 

 line of ferns, just as in the living ferns, the two 

 heterosporous families, the Marsiliaceae and Sal- 

 viniacese, are of obviously independent origin. 



Among the fossil club-mosses of the Carbonifer- 

 ous, there are also unmistakable evidences of seed- 

 bearing genera, such as Lepidocarpon, which pre- 

 sumably was related to the great tree-like Lepido- 

 dendrons. In many ways these seed-bearing club- 

 mosses suggest the peculiar conifers of the South- 

 ern Hemisphere, Araucaria and Agathis, and it is 

 not impossible that the prevailing modern Gymno- 

 sperms, the conifers, are the descendants of some 

 of the tree-like Paleozoic club-mosses. It must 

 be noted, however, that this view is strongly op- 

 posed by some eminent students of the Paleozoic 

 fossils. 



