2 MR. F. N. WLLLIAMS ON THE GENUS SILENE. 
the valuable contributions to our knowledge of the genus by 
Godron,* Willkomm,t and more especially Boissier,t dealt 
with the species of definite geographical areas; and the pro- 
visional schemes of classification put forward by each of them, 
as well as their grouping of species, were based on what 
appeared to be the primary characters, not of the known 
species of the whole genus, but of those which were found 
within a definite area. On account of the great number of: 
species which were described after the publication of the first 
volume of the ‘Prodromus,’ the literature of which was 
scattered in various works in many languages, it became very’ 
desirable, as Rohrbach says, in spite of the difficulties of the 
subject, that a revision of the genus in the form of a systematic 
monograph should be undertaken by a botanist who was willing 
to devote time and labour to the work, both in examining the 
material, in overhauling and collating the authorities, and in 
bringing together and codifying on a uniform plan the scattered 
descriptions of the species. 
It is more than a quarter of a century since Paul Rohrbach 
(whose early death from consumption cut short a promising 
career and was a great loss to science), at the suggestion of 
Grisebach and under the direction of Alexander Braun, 
enriched systematic botany with an elaborate analysis of the 
genus Silene. It would be beside my purpose to expatiate 
on the merits of this memoir, and it is with much diffidence 
that I have essayed to revise it. Since 1868 a large number 
of new species have been described (especially from Eastern 
countries), and much material for the elucidation of previously 
described species has been accumulated and in part examined : 
the re-adjustment of groups of species has proceeded with the 
exariination of new material: the affinities of species among 
themselves, both in their relation to systematic position and to 
geographical distribution, have been more critically studied : 
and in a matter subsidiary to these, in the direction of precision 
and uniformity, conflicting schools of nomenclature have for- 
mulated and codified their rules, requiring here and there a 
change of name; so that in a revision of the genus, much has 
to be 1e-considered. 
* Obs. crit. sur Vinflor. du genre Silene (1847). 
+ Ic. Descr. Pl. Noy. Crit. Rar, Hispanie, i, p. 73 (1853). 
t FI. Orientalis, i, py . 567-657 (1867). 
