224 SCIENCE PROGRESS 



were they not ferns, as even specialists in fossil botany fully 

 believed until recently, but they had attained to the very 

 different rank or status of seed-plants. In brief, the discovery 

 of this significant fact forms the greatest contribution to fossil 

 botany within modern times. We know now beyond doubt 

 that most of these fern-like plants of Carboniferous age were 

 Gymnosperms, and not Cryptogams. 



It would take too long here, nor would it be advisable, 

 to try to illustrate even the fundamental botanical differences 

 between the seed-plants, of which the Gymnosperms are 

 one group, and the Cryptogams. A rough analogy may, 

 however, serve to give some conception of the gap which 

 separates these two races of the Vegetable Kingdom. In the 

 animal world, living and extinct, two great subdivisions are 

 easily distinguished — the Vertebrata, or animals having a " back- 

 bone," and the Invertebrata, which do not possess a spinal 

 column. Partly on these grounds, but in reality for many other 

 reasons, the Vertebrata are generally regarded as having attained 

 to a far higher position in the scale of morphological develop- 

 ment and complexity than the Invertebrata. 



In the Vegetable Kingdom there may be found a superficial 

 analogy. The seed-plants (Spermopliyta) correspond roughly to 

 the Vertebrata among animals, while those plants — including the 

 Algae, Mosses, and Ferns — which possess the type of reproduc- 

 tion termed Cryptogamic, lie roughly parallel to the Invertebrata. 

 In both kingdoms there are further subdivisions, or races — the 

 Reptiles, Birds, Fishes, and Mammals among Vertebrata, and the 

 Gymnosperms and Angiosperms among Spermophytes. The 

 highest plants— the Angiosperms, or Flowering Plants — corre- 

 spond to the Mammals among Vertebrata. 



Now, if a fossil had been discovered, let us say resembling 

 externally a Crustacean — the group of Invertebrata to which the 

 Lobsters and Crabs belong — which in addition to a tough outer 

 skeleton (exoskeleton) possessed a bony spinal column, the main 

 conclusion that an animal had been found, closely resembling an 

 Invertebrate, but which was in reality a Vertebrate, would be of 

 great interest to zoologists, and to the scientific world in general. 

 In the case of these seed-bearing, fern-like plants, this is roughly 

 what has happened. What was formerly regarded as a Fern has 

 proved to be a Gymnosperm, two stages, let us say equivalent, 

 in imagination, to the Crustacea among Invertebrata, and to 



