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MR. Fe. N. WILLIAMS ON THE GENUS SILENE. 1y 
which, while, for example, in Dichasiosilene distinguishes the 
series Awriculate from all the other perennial species of the 
section, in some species is to be found in all stages of transition 
from slight broadening at the apex of the claw to the develop- 
ment of a distinct lobe on each side of it. The degree of segmen- 
tation in the blade, the width of the lobes, and lastly the colour of 
the petals are not characters which may serve for the separation 
of species, apart from other and more distinctive characters. 
Of still less importance is the general pubescence of the 
plant; which, as is well known, is a character that often 
depends on external conditions, and on difference in station and 
in vertical range. Somewhat more constant and reliable is the 
pubescence of the calyx, though this is subject to considerable 
variation. The least important, or which amounts to the same 
thing, the most unreliable character to make use of in the 
limitation of species is that of the form of the foliage-leaves. 
Although this has been long recognised by systematic botanists, 
in a genus like Silene, it is necessary to emphasize the fact; to 
justify, for example, the circumscription of S. chlorefolia, whose 
aberrant forms present indeed a very diverse type and appear- 
ance, forms which Rohrbach thought desirable to include in 
this species, and, as he shows in his diagnosis, by a continuous 
series of intermediate forms are connected one with another, 
which makes a separation into four distinct specific types 
scarcely feasible or possible. In the same way and by the same 
variable character is justified the inclusion of several forms 
(superficially distinct) within the limits of a species. 
In giving greater importance to the presence or absence of 
the coronal appendix, I venture to differ from Rohrbach, as 
modifications of it have a systematic value in other genera. 
ITI. Puan anno Scope or tuts Revision. 
The Revision of the genus is based on Rohrbach’s Monograph, 
published in 1868. Specimens of most of the species described 
by him have been examined, excepting only those of which 
authentic types were not obtainable for examination. Species 
have been transferred from one group to another, only after 
examination of properly authenticated specimens and the 
remarks on their structural character by other observers have 
satisfied me that occasional deviation from the sequence in 
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