378 Mr. MiERs 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 Burmanniaceco ; 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- 

 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 ; but in 

 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 cellf ; while in Dictyostega, as before mentioned, 



* See Linn. Trans, vol. xviii. p. 537. Tab. XXXVIII. fig. 3, a. 



t I ™ay 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 placentae 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 



