1s Mk. F. N. WILLIAMS ON THE GENUS SILENE. 
sperma is in the structure of the seed. Of not less importance 
as a character is the nervation of the calyx, especially in respect 
of the branching of the ten primary nerves. The presence or 
absence of such anastomosing branches is a variation net 
altogether unknown within the limits of the same species; yet 
by this character is S. linearis separated from S. arenosa. Of 
often more than specific importance is the form of the fruc- 
tiferous calyx, as to whether it is contracted and almost closed 
above, or uniformly cylindrical, or campanulate and expanded 
under the reflexed petals. 
Again, to take an example from other organs, within the 
same group of species, the filaments, which are usually glabrous, 
in a number of species are invested with long cilia. 
As to the duration of the life of the piant, this seems a fairly 
constant and reliable character; likewise the manner of growth, 
whether uniaxial (as is generally the case) or biaxial. As an 
exception under abnormal conditions, we may instance S. ciliata, 
in which the flowering stems are terminal, but which under 
cultivation sometimes produces a main axis with infrarosular 
flowering stems as in S. melandryoides. The form of the 
different calyx-teeth varies sometimes in the same flower ; since 
this, however, is associated with other characters in the structure 
of the calyx, it is therefore of value in separating species. On 
the contrary, should such variation be found in individuals of 
what are supposed to be the same species, then analogy must 
decide whether it is desirable to separate the two as distinct 
species. In this connection may be noted the form of the calyx, 
which at the time of flowering is often very different from that 
which incloses the ripe capsule. 
As to the form of the capsule, and the relative length of the 
capsule and carpophore, the variations within certain limits to 
which both are subject are different for different groups, and 
their importance as a character can only be ascertained and 
appraised by comparison in the different groups. On the other 
hand, the presence of cilia on the claws of the petals is a 
character subject to variation more often, even in the flowers 
of the same stem; especially is this noticeable in the group of 
S. Sazxifraga, while in most other groups the character of 
“ungues glabri”’ and “ ungues ciliati”’ is sharply defined. The 
same obtains in the definite character of the auriculate appen- 
dage or dilatation at the junction of the claw with the blade, 
