50 ON GENERA AND SPECIES. 
extended only to Goniophlebium, 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 
Linneus, 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 à - 
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’ 
“Genera Filicum,” which commenced with a set of draw 
ings begun in 1833 by the late eminent botanical buon 
 |man Francis Bauer, from specimens from time bi n 
