378 Mr. Mizns on a new Genus of Plants 
will of course require some modification, in order to embrace them within its 
limits. The dehiscence of the pericarpium in the two genera under conside- 
ration, which, on a cursory glance, seems greatly at variance with the usual 
character of the order, will not, on closer examination, appear so very incongru- 
ous ; for if we assume an instance where the capsule bursts after the manner of 
that of Gonyanthes*, and imagine in such case the perianthium to be not only 
wingless, but destitute of the strong nerve upon which each wing is formed, : 
the result would occur as in Ophiomeris and Thismia, the circumscissure of 
the tube and the opercular dehiscence of the fruit; and from the little we 
know of Blume's genus Gymnosiphon, we have reason to suppose its capsule 
bursts in a somewhat similar manner. In Dictyostega, the 3 strong ribs 
which proceed from the base of the ovarium, and remain attached to the wall 
of the cell, bearing in their middle the clustered placentations, continue their | 
course along the disc, and again become united in the persistent style; in 
consequence of which the dehiscence takes place, as in Burmannia, by the 
disruption of the weaker membranous portions between the 3 persistent ribs. 
In Cymbocarpa, in consequence of the gibbous form of the ovarium, the de- 
hiscence is caused by a single longitudinal laceration along its weaker side. — 
In fact, in no instance, as far as I am aware, is there any approach to the 
ordinary valvular dehiscence in Burmanniacec ; Cymbocarpa offers certainly 
the nearest approach to it, but in all cases the bursting of the cell is effected 
by a mere laceration of its reticulated membrane, varied in different cases by — 
the absence or interruption of the placentary ribs, or the intervention of dis- m 
sepiments: in most instances this occurs rather in the sides of the capsule, on 
account of the greater tenuity of the membrane as it becomes dried; butin - 
Ophiomeris and Thismia this takes place by the laceration (in an opercular 
form) of the disc, which is there more membranaceous than the comparatively : 
fleshy wall of the unilocular cellt; while in Dictyostega, as before mentioned, 
* See Linn. Trans. vol. xviii. p. 537. Tas. XXXVIII. fig. 3, a. “a 
t " may here observe, although I had an opportunity of examining only a single dried capsule of 
Ophiomeris, that notwithstanding the disc had fallen off, as shown in fig. 14, it appeared to me there 
came away with it, after being moistened, a detached and somewhat gelatinous 3-lobed process, which 
perhaps formed an extension of the placente beneath the disc, which showed no indication whatever 
of any nervures on its surface; the style also that remained attached to the disc was now quite hol- : 
low and reduced to a thin fistular tube, leaving an uninterrupted channel through the open stigma 
