PROGRESS IN PALAEOPHYTOLOGY 167 



plant and its affinities with the Angiosperms was worked 

 out by the American palaeobotanist Wieland in the 

 beginning of the twentieth century, but his conclusions 

 may be left for future discussion. 



The names that stand out most prominently in fossil 

 botany between 1860 and 1890, however, are those of 

 Williamson in England and Renault in France. William- 

 son's name is inseparably associated with the plants of the 

 coal measures, and to him and to his coadjutor of later 

 years, Scott, we owe a long series of monographs that 

 rank in importance with those of Hofmeister and Bower 

 as classics in the history of our knowledge of the Vascular 

 Cryptogams. Williamson devoted himself more especially 

 to proving, ultimately with complete success and in 

 opposition to the French school, that the stems of 

 Calamites, Lepidodendron, Sigillaria, etc., although they 

 exhibited secondary thickening, were neither Angiosperms 

 nor Gymnosperms but genuine Vascular Cryptogams. 

 He further showed that the fossils known as Stigmaria 

 were not only roots of Sigillaria but also of Lepidodendron. 

 He also worked out the anatomy of a fossil stem called 

 Lyginodendron, which had been discovered by Binney 

 in 1866, and emphasised its Pteridophytic relationship, 

 while admitting at the same time that it showed distinct 

 Cycadaceous affinities. This type was destined some 

 years later to form the basis of an entirely new group of 

 plants, the Cycadofilices or Pteridospermae, but the full 

 story of the recognition of this family we shall discuss 

 later on. 



In France Renault's name is associated first of all 

 with the anatomy of the fossil Pteridophyte known as 

 Sphenophyllum, a genus found later to be allied to the 

 Equisetales, and also with Sigillaria, the structure of 

 which he investigated with Grand 'Eury in 1874. To 

 Renault also we owe much of our knowledge of the most 

 primitive ferns, the Botryopteridae, and of many fern-like 

 fronds that were regarded at that date as allied to Marat- 



