MANTON: PTERIDOLOGY 307 



1888, etc.) and then tlic work spread to England, America, and Holland. 

 An excellent historical survey of the contribution made by van Tieghem and 

 his immediate successors was published in 1902 by Schoute in a book which 

 also did much to standardize our present terminology by, among other things, 

 sweeping away one of van Tieghem's less felicitous concepts, namely, the 

 attribution of polystely to the ferns. Schoute's bibliography is instructive. It 

 includes Jeffrey (1897) for the invention of the words "protostele" and "sipho- 

 nostele," Gwynne-Vaughan (1897) for the introduction of the word "meristele"; 

 Gwynne-Vaughan again in 1901 for the word "solenostele" and Brebner (1902) 

 for the word "dictyostele." Brebner's paper contains an extensive and interesting 

 glossary of contemporary anatomical terms, many of which are still in use, and 

 Jeffrey's paper is of special interest for the clear statement (Jeffrey, 1897, p. 

 869; elaborated later in Jeffrey, 1903) : 



In the Filicales the siphonostelic modifications arose in connection with the support of 

 large leaves, and hence is called phyllosiphonic. In the Lycopodiales, and probably the 

 Equisetales, it is related to the support of branches and hence may be termed cladosiphonic. 



The implications inherent in this point of view became more generally recog- 

 nized twenty years later. 



The work of the British school of plant anatomists headed by F. 0. Bower 

 has been so excellently summarized by the numerous publications of that author 

 (Bower, 1908, 1923, 1926, 1928, 1935) that it need not be discussed in detail. 

 For an independent summary of the position at the time of the publication 

 of the Land Flora, reference may be made to Tansley (1908), and for the 

 position twenty years later there is Schoute (1938). 



Concurrently with the advance in knowledge of the anatomy of living mem- 

 bers of the group, the anatomical study of fossils has been a development of 

 the first importance. A pioneer in this field was Williamson (1871-1883), with 

 Renault in France as an almost exact contemporary. At a later date William- 

 son collaborated with D. H. Scott (1894-1895) after which Scott carried on 

 alone (1897 et seq.). To these authors we owe the first clear outlines of the ana- 

 tomical structure of the main pteridophyte constituents of the coal-measure 

 flora, together with those which we now know to have been seed plants but 

 which at that time were thought to be fern-allies of the group Cycadofilices. 



The effect of this work on the taxonomic system is at once displayed in Eng- 

 ler and Prantl, Die naturlichen Pflanzenfamilien, of which the first parts of the 

 volume on Pteridophyta appeared in 1898. This contains a supplement on the 

 fossils of Potonie and the main groups recognized (both living and fossil) are 

 as follows: 



Class I. Filicales 



1. Leptosporangiatae (10 families of ferns including Marslleaceae and Salvinia- 

 ceae) 



2. Marattiales 



3. Ophioglossales 



StTPPLEMKNT ON SIPPOSED FOSSIL FERN LEAVES 



Class II. Sphenophyllales 

 Class III. Equisetales 



1. Equisetaceae 



2. Calamariaceae 



