THE ORIGIN OF GYMNOSPERMS 225 



Fishes or Birds among Vertebrata. This illustration must not, 

 of course, be taken literally. It may, however, serve to give 

 to those who are not specially familiar with the characters of 

 the subdivisions of the Vegetable Kingdom, some idea of the 

 enormous gap which the botanist perceives between the two main 

 subdivisions of that kingdom, the Cryptogamic and the Spermo- 

 phytic ; hence the interest of the present subject, the origin of 

 certain seed-plants from ancestors which did not bear seeds. 



But to return to our Carboniferous fern-like fossils. The first 

 suspicion that in these cases we may be dealing with plants, 

 which are not really ferns at all, suggested itself to the 

 Austrian palaeobotanist Stur in 1883. The fact that a fern-like 

 fructification had never been observed on the fronds of any of 

 the thousands of examples of Alethopteris or Neuropteris which 

 had been collected at one time or another, led Stur 1 to the 

 conclusion that whatever these plants may have been, they were 

 certainly not ferns. But for twenty years afterwards no definite 

 evidence was forthcoming as to the precise nature of the fruc- 

 tifications of these plants. 



Meanwhile progress was being made in what seemed to be 

 other directions, though, in respect at least to one group of 

 fossils, it subsequently proved that this apparently new direc- 

 tion was in reality identical with the old. 



The study of Carboniferous petrifactions, i.e. plant remains 

 in which the internal structure is preserved, begun in this 

 country by Witham and Binney, but finding its greatest ex- 

 ponent in Williamson, had already commenced to make rapid 

 progress. Among the members of the Carboniferous vegetation 

 investigated by Williamson, 2 and subsequently by that botanist 

 in conjunction with Dr. Scott, 3 were certain fossils known as 

 Lyginodcndron and Hetcrangium, which possess a peculiar type 

 of structure, combining features common both to living ferns 

 and also to living Cycads. Other genera also possessing this 

 peculiarity had been discovered by Continental workers, as well 

 as by British investigators. 4 By the year 1898 it had become 

 clear that there existed a considerable plexus of such plants in 

 Carboniferous and Permian times, and for this group Professor 

 Potonie, 5 of Berlin, proposed the appropriate name, Cycadofilices, 

 thus indicating the synthetic nature of their morphology. 



1 Stur, 1883, p. 638. 2 Williamson, 1873. 3 Williamson and Scott, 1895. 

 4 Scott, 1899. * Potonie, 1897, p. 160. 



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