NATURAL ORDERS. 117 



incompletum, only one circular membrane exists, with the 

 unilateral rudiment of the second. 



The rudiment of the inferior membrane in this species 

 points ont the relation 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 interme- 

 diate structure of an unpublished plant of this order from 

 Sierra Leone, in Sir Joseph Banks's herbarium^ in which 

 the nearly similar squamge, though distinct, are disposed 

 in a single complete circle ; and by Melastoma octandra of 

 Linnaeus, in which they are only four in number, and alter- 

 nate with the proper divisions of the calyx. . 



The two species here referred, though improperly, to 

 Rhexia, agree with a considerable part of the species pub- 

 lished 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 uni- 

 formly over the whole surface, is limited to ten longitudinal 

 equidistant lines or membranous processes, apparently 

 originating from the surface of the ovarium ; the inter- 

 stices, which are tubular, and gradually narrowing towards 

 the base, being entirely free. 



The function of these tubular interstices is as remark- 

 able as their existence. 



In Melastomacese, before the expansion of the corolla, the 

 tops of the filaments 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 complete 

 cohesion between the calyx and ovarium, where that exists ; 

 or, where this cohesion is partial, and such as I have now [«6 

 described, being lodged in the tubular interstices ; their 

 points extending to the base of the ovarium. Prom these 

 sheaths, to which they are exactly adapted, the antherae 

 seem to be disengaged in consequence of the unequal 

 growth of the different parts of the filament ; the inflected 

 portion ceasing to increase in length at an early period, 

 while that below the curvature continues to elongate con- 



