APPENDIX. No. V. 435 
‘The second is perhaps not distinct from Melastoma decumbens, of the same 
author.* 
_ The third and fourth are new species referable to Rhewxia, as characterised 
by Ventenat,+ though not to that genus as established by Linneus; and in 
some respects differing from the species that have been since added to it, all 
of which are natives of America. 
In the original species of T'ristemmat there are, in the upper part of the tube 
of the calyx, two circular ciliated membranous processes, from which the 
name of the genus is derived; the limb of the calyx itself being considered as 
constituting the third circle. 'The two circular membranes are also represented 
as complete in 'T. hirtum. 
But in the species from Congo, which may be named 7’. ¢ncompletum, only 
one circular membrane exists, with the unilateral rudiment of the second. 
The rudiment of the inferior membrane in this species, points out the rela- 
tion between the apparently anomalous appendage of the calyx in Tristemma, 
and the ciliated scales irregularly scattered over its whole surface in Osbeckia ; 
the analogy being established by the intermediate structure of an unpublished 
plant of this order from Sierra Leone, in Sir Joseph Banks’s herbarium, in 
which the nearly similar. squame, though distinct, are disposed in a single 
complete circle; and by Melastoma octandra of Linneus, in which they are 
only four in number, and alternate with the proper divisions of the calyx. 
The two species here referred, though improperly, to Rhexia, agree with a 
considerable part of the species published in the monograph of that genus by 
M. Bonpland, and with some other genera of the order, in the peculiar manner 
in which the ovarium is connected with the tube of the calyx. This cohesion, 
instead of extending uniformly over the whole surface, is limited to ten longi- 
tudinal equidistant lines or membranous processes, apparently originating from. 
the surface of the ovarium ; the imterstices, which are tubular, and pracually 
narrowing towards the base, being entirely free. 
The function of these tubular interstices is as remarkable as their existence. 
In Melastomacez, before the expansion of the corolla, the tops of the fila- 
ments are inflected, and the anther: are pendulous and parallel to the lower 
or erect portion of the filament ; their tips reaching, either to the line of com- 
plete cohesion between the calyx and ovarium, where that exists; or, where 
* Op. citat. 1, p. 69, t. 49. + Mém. de VU Insliiut. sc. phys. 1807, prem. semest, p.11- 
~ Tristemma yirusana, Vent, Choix de Piantes 35. 
