APOSTASIACEZ OF THE MALAY PENINSULA. 317 
referred to Vandew. The pollinia, however, are not those of 
any Vandea, but seem to be not very much modified from those 
of some species of Tainia, to which genus Plocoglottis in 
other respects seems most nearly allied. 
In P. porphyrophylla, Ridl., the pollinia consist of four 
kidney-shaped masses of rather pulverulent pollen, attached 
by their inner edges to stalks, of which two are longer than 
the others; these end below in a mass of roughly triangular 
outline. Both the stalks and this disc-like mass are of a yellow 
colour, and contain much pollen mixed with viscid matter; and 
it appears that the supposed disc rather corresponds to the two 
lowest pairs of pollinia of such a plant as Tainia speciosa, 
Blume, than to the viscid disc of, say, a Saccolabium. A large 
mass of white viscous matter overlies the rostellum, and, 
becoming readily attached to the pollinia, acts as a viscid disc. 
The arrangements for insect fertilization are very curious, and 
differ from any other species known to me. 
The flowers open singly, two or three at a time, in all I have 
seen, though Blume figures the whole raceme open at once in 
several species. They are of dull colour, often purple and 
yellow, and one species at least (P. fetida, Ridl.) has a most 
unpleasant carrion odour. Hence one would expect them to be 
fertilized by Diptera, which is indeed the case. In P. porphy- 
rophylla, Ridl., the flowers open wide; the dorsal sepal and 
petals are narrow and yellowish coloured, and are thrown back 
when the flower expands. The column is arched over the lip. 
The lateral sepals are much larger than the dorsal one, of a 
bright purple colour, polished, and the most conspicuous part 
of the flower, their inner half, is thickened and involute. The 
lip is broad and shorter than the sepals. It has a yellow 
ground, thickly marbled with red; the basal edges are thinner 
in texture, yellow with black spots, and fringed with small 
processes. The apex of the lip is very broad, and the outer 
angles project a short distance. On the disc near the angles 
are a pair of shining, deep purple horns, which resemble drops 
of nectar. In the bud, the lip lies flat against the column, but, 
as the flower opens, it is drawn down in such a manner as to 
lie flat at some distance below it. This is effected by the 
lateral sepals, the thickened inner edges of which overlap the 
prolonged angles of the lip, and, as they are deflexed, draw 
down the lip. When a fly alights on the lip in search of 
