552 . Mr. Miers on some new Brazilian Plants 
placentæ, a relation most usual in cases of compound unilocular ovaria where 
the number of stigmata and placente is equal; and that such is really its 
relation appears to him to be proved by tracing to their origin their vascular 
cords, which are found to coalesce with those of the three outer foliola of the 
perianthium. This view of the composition of the ovarium in Orchideæ, he 
observes, is confirmed by finding that it agrees with the ordinary arrangement 
of Monocotyledonous plants, viz. the opposition of the double parietal pla- 
centæ to the three inner divisions of the perianthium, while in 4postasia the 
three placentæ of the trilocular ovarium are opposite to the three outer divi- 
sions. The same agreement, he further observes, is found in Scitamineæ, both 
in the placentze of the trilocular ovarium, which in this family is its ordinary 
structure, and in the unilocular, which is the exception. My observations 
upon the structure of Burmanniacec afford to that order a different arrange- 
ment as regards the position of stigmata. Dr. Von Martius, in illustrating 
the genus Burmannia, has given a figure of the pistillum of B. bicolor, in 
which the stigmata are placed opposite to the wings, and therefore alternate 
with the inner segments of the perianthium ; but this probably may have been 
an error of the draughtsman, since no such position is alluded to in the text. 
I have in several instances opened with the utmost care the flowers of Bur- 
mannia, and have found the stigmata manifestly placed as I have constantly 
observed them in Dictyostega and the allied genera with unilocular capsules, 
viz. opposite to the stamens, and to the inner segments of the perianthium, with 
which the placentze also correspond, all being alternate with the outer seg- 
ments: in Burmannia, however, owing to the complete inflection of the car- 
pellary leaves to form the trilocular ovarium, the placentæ thus extended 
to the axis will be seen directed towards the middle of the cells, and opposite 
to the outer segments of the perianthium, at the same time that all other parts 
remain as before mentioned, in a similar position to that existing in Dic- 
tyostega. 
This deviation from the usual order of relation may probably be accounted 
for by the very ingenious views of Mr. Brown relative to the original compo- 
sition of stigma, founded on the supposition that each simple pistillum or 
carpel has necessarily two stigmata, which are to be regarded not as terminal, 
but lateral, in the same manner that the placentæ of each carpellary leaf are 
