MAGNITUDE OF HIS OUTPUT 257 



to Lepidodendron, besides other allied forms, and placed our 

 knowledge of the comparative anatomy, once for all, on a broad 

 and secure basis. His great monograph of Stigmaria, by some 

 considered his best work, is still our chief authority for the sub- 

 terranean organs. 



In the Ferns he made important contributions to our know- 

 ledge of the group now familiar to botanists as the Primofilices 

 of Arber. In particular his account of the plant now known as 

 Ankyropteris corrugata is still among the best we possess of any 

 member of the family. 



In Pteridosperms, to use the modern name, Williamson may 

 fairly be called the discoverer of the important family Lygino- 

 dendreae. He appreciated their intermediate position, speaking 

 of them, in 1887, as "possibly the generalised ancestors of both 

 Ferns and Cycads." 



As regards both Pteridosperms and Gymnosperms proper, 

 attention may be specially called to his work on isolated seeds, 

 in which he was surpassed by Brongniart alone. This field 

 of investigation, long neglected, has lately been revived with 

 striking results. 



I hope that all students of fossil botany will have at least 

 turned over the pages and the plates of Williamson's works, for 

 only by inspection of the original memoirs can any idea be 

 gained of his vast services to our science. 



His remarkable skill as a draughtsman (for all his memoirs 

 are illustrated by his own hand) is not always done justice to in 

 the published reproductions as the fine examples of his original 

 drawings, so kindly lent for the lecture by Mrs Williamson, will 

 show 1 . At the time when Williamson's main work was in pro- 

 gress from 1870 to 1892 geologists were probably more 

 appreciative of its value than botanists. Happily, in spite of 

 occasional trouble with Referees, none of his work was lost, the 

 Royal Society going steadily through with all the nineteen 

 memoirs which were entrusted to them. 



The one botanist, who, up to the year 1890, estimated 

 Williamson's work at its full value was Count Solms-Laubach, 



1 Three characteristic figures from these originals have been reproduced for this 

 volume (Plates 22-24). 



O. B. 17 



