MR. F. N. WILLIAMS ON THE GENUS SILENE. 11 
or the other parent; and there is often a difference in the 
result in reciprocal fertilizations. Moreover, certain hybrids, 
such as those of Datura, which are fully fertile per se, divide in 
the offspring, partly in the first generation, and completely in 
two or three succeeding generations, into the two component 
species, even when close-fertilized. 
In discussing the crossing of Melandrywm rubrum, Garcke, 
and Melandryum pratense, Rohl., with Silene viscosa, Pers., 
Rohrbach draws conclusions as to the greater sexual affinity 
between Melandryum and Silene, than between Lychnis and 
Silene; but in this particular instance it does not apply, as 
L. Celakovsky has shown that in ¥S. viscosa the capsule is truly 
unilocular, and not more or less septate at the base, and that 
therefore this species should be transferred to Melandryum. 
If then we take into consideration the number of the styles, 
and the number of the teeth formed by dehiscence of the ripe 
capsule, we find that the following genera are isotypic with 
these three :—Hudianthe, Viscaria, Heliosperma, Petrocoptis, and 
lastly Coronaria. 
A tabular conspectus of the genera here mentioned will best 
illustrate their differential diagnosis :— 
Tribe Lychnidew (or Silene), Subtribe Silenoidee. 
A. Capsule unilocular. 
a. Carpels alternate with the teeth of the 
calyx. Anthophore none. Styles 5. 
Capsule 5-dentate . AGROSTEMMA. 
b. Carpels opposite the teeth of the calyx. 
Anthophore conspicuous, often elon- 
gated. 
a. Capsule dehiscing by teeth equal in 
number to the styles. 
* Petals convolute in preefloration. 
Appendices fornicate at the base ... LycHNIs. 
** Petals convolute in _ preefloration. 
Appendices efornicate at the base.. CORONARIA. 
*** Petals imbricate in preefloration. 
Seeds bearded at the hilum .. PETROCOPTIS. 
fB. Capsule dehiscing by twice as many 
teeth as the styles. 
* Seeds crested on the dorsal surface. 
Styles 3 oe ..- HELIOSPERMA. 
** Seeds not crested on the dorsal 
surface. Styles 5, rarely 3 ..  MELANDRYUM. 
