50 ON GENERA AND SPECIES. 



extended only to Goniophlebinm, being the seventy-third 

 genus in alphabetical order, up to which are enumerated 

 1,738 species with their synonyms ; from this data it may 

 be calculated that the number of species, when the work is 

 complete, will amount to above 4,000. As an instance of 

 the labour and investigation required, I will select the 

 genus Acrostichum. Under this original generic name of 

 Linnaeus, no less than 461 specific names are enumerated 

 in alphabetical rotation, with references to their authorities, 

 occupying twelve pages : with the exception of nine names, 

 the whole are in italics, signifying that they are synonyms, 

 the nine being in roman type, indicating that they are the 

 only true species of Acrostichum as now adopted. When 

 complete, this work will be an invaluable treasure to 

 Pteridologists. 



I have now to notice the works of Sir William Hooker , 

 who in 1820 became Professor of Botany in the University 

 of Glasgow, and in 1841, Director of the Royal Gardens 

 at Kew, but before the first date he had gained reputation 

 as a cryptogamic botanist. His first great work on Ferns 

 was in conjunction with Dr. Greville, of Edinburgh, also a 

 famous cryptogamic botanist, entitled " Icones Filicum," a 

 work of two folio-sized volumes, containing 230 finely 

 executed plates of new and rare Ferns, each plate con- 

 taining magnified portions of the fructification exhibiting 

 the characters of the genera as then defined, with accom- 

 panying descriptive letter-press. In this work two new 

 genera are characterised, viz., Deparia and Jamesonia, each 

 founded upon a single species. 



His next work of importance is Hooker and Bauer's 

 *' Genera Filicum," which commenced with a set of draw- 

 ings begun in 1833 by the late eminent botanical draughts- 

 man Francis Bauer, from specimens from time to time 



