328 Ridley . — On the method of fertilization in 
B. macrantkum , Lindl. In this species the following organs 
are concerned in the process of fertilization. The lip is very- 
small in proportion to the sepals. It is a curved tongue- 
shaped fleshy organ, acute at the apex and squared at the 
base, where it has two little projecting angles or ears, and a 
central groove. It is light yellow, the apex speckled with red, 
and is not smooth and polished like the sepals. The squared 
base is notched and balanced upon the apex of the column- 
foot, so that it hangs half through the aperture between the 
two sepals. It is prevented from falling quite through by the 
little ears which rest on the inner edges of the two sepals. 
It moves easily backwards and forwards upon its hinge, 
but in whatever position the flower is held, the lip always re- 
mains in the normal position, as shown in Figs. 3, 4, the centre 
being 4 mm. from the column. But a certain amount of weight 
placed between the ears causes it to fall backwards towards 
and nearly to touch the column. The column is a little 
more than 5 mm. in height, stout, and rounded at the back. 
The stelidia are short triangular processes, rather thin in 
substance but stiff; they stand out towards the lip, but slightly 
converge together at the apices, which are 2 mm. apart. 
The anther is sunk in the clinandrium, and turned on its 
back, so that the apex touches the back of the clinandrium and 
the pollen-disc is exposed between the two stelidia. The 
pollen-masses are two, rather large, bright yellow, semi-trans- 
parent, pyriform, curved, bilobed. 
The column is yellow, with a fairly long up-curved foot, 
the apex of the anther is red. From the position of the foot, 
which is curved upwards nearly to the height of the stigma, 
the squared base of the lip stands a little above and at some 
distance (4 mm.) from the stigma and pollen. 
The fertilizer of this orchid is a small and active fly (Dip- 
teron) ; it is diurnal, and delights in bright sunshine. I have 
seen it invariably close by when this plant is in bloom, and it 
also makes its appearance when Dendrobium superbum and 
another smaller flowered Sestochilous Bulbophyllum , which I 
1 Bot. Reg., 1844, t. 13. 
