2 Scientific Proceedings, Royal Dublin Society. 



found ferns were regarded as members of or as allied to these two groups of 

 Eu-Sporangiatee and to the Oyatheacese/ A great many of these " ferns " 

 were, however, early iu the last century, noticed to be sterile; and, according 

 to Lotsy, Austen in 1849, at a meeting of the British Association, sought to 

 explain this by tlie suggestion that the temperature in the Carboniferous 

 epoch was too low for fructifications to be formed. One of the most beautiful 

 of these ferns is Sphenopteris affinis, which, as Seward recalls, appears as 

 the frontispiece in Hugh Miller's " Testimony of the Kocks." I find that, in 

 describing the fern. Miller mentions that it possessed peculiarities exhibited 

 by no fern then living (1857), according to the botanists of the day whom 

 he consulted. One of these lie mentions in another part of the book by 

 name (Professor J. H. Balfour, of Edinburgh). Hugh Miller's is the first 

 suggestion I have seen that the ferns forming half the flora found in the 

 Upper Devonian and Carboniferous deposits, were not altogether fern-like. 

 In 1883 Stur, after twenty years' devotion to Palseo-botany, emphasized 

 this idea, and placed aside, in a group which he called " Niehtfarne," for 

 subsequent description, many forms at that time included with the Ferns. 

 As a result of the investigations of the structure of such forms, Potonie, 

 finding characters suggesting in some respects fern- and in other Cycad- 

 affinities, created in 1897 a special group for them, which he called the 

 Cycado-FUiccs, in which one authority would place all the Devonian and 

 Lower Carboniferous " Ferns." Of these forms one of the most interesting 

 is Lyginodeitdron oldhamium, whose stem Williamson described in 1873. In 

 1874 he described its petiole as Raehiopteris aspera, suspecting, however (as 

 he found later to be the case), that it was part of Lyginodendron oldhamium. 

 Later on Kidston found that a fossil fern whose foliage liad been described 

 by Brongniart under the name of Sphenopteris Hdainghausi was, in reality, 

 the foliage of Lyginodendron. l^hus three different parts of one type had 

 been described under three distinct names. In 1894 Williamson and Scott 

 completed the story of the discovery of the vegetative organs by showing 

 that the roots Kahxylon Hooheri were the adventitious roots of Lyginodendron 

 oldhamium. 



It would be out of place here to give more than a summarized account of 

 the vegetative organs of Lyginodendron. Readers may consult the articles 

 contributed by Williamson and Scott to the Philosophical Transactions of 

 the Royal Society in 1894 and 1896, and especially the well-illustrated, 



it is now thought, mostly Pterido^perms, and there is, it is stated, little evidence even in Mesozoic 

 rocks of the Eusporangiate type. In a forthcoming paper on Archaopteris I hope to discuss this 

 question. 



' Stur regarded Calymmotheca ( which Zeiller corrects to Calymmatotheca) as one of the CyatheaceEe. 

 His two genera of the Ophioglossaceje have their position as such questioned to-day. 



