African and Madagascar Flowering Plants. 347 
groove in the vexillum. The stamens are differentiated into 
two distinct whorls, of which those with the shorter anthers 
push up the pollen as in the Lupine. The style is protected 
from its own pollen by hairs on its inner surface. On depres- 
sion a thin streak of pollen exudes from the drawn out conical 
end of the carina, and subsequently the stigma appears. The 
honey is protected by the thick, flat, and rigid vexillum-claw 
which fits over the entrance. Visitors : — Xylocopa cajfra and 
Apis mellifica , both ab. 
Crotalaria retusa, L. (Figs. 61, 62.) 
Very similar to the preceding, but with the vexillum- 
claw even more specialised to cover the honey entrance. 
I also found that in the buds the vexillum completely covers 
the carina, the sides being wrapped together in front, and 
in consequence of this the style, which is at first directed 
obliquely upward from the end of the ovary, is unable 
to develop, and therefore takes the peculiar downward 
curve (see Figs. 58, 64), and which is characteristic of the 
genus. After the vexillum has been freed from the carina, 
no further elongation of the style takes place. Visitors : — 
Hymenoptera : (probably Xylocopa violacea ), Allodape Elliotii , 
De Sauss., standing on vexillum and sucking head downwards. 
Diptera : Philanthes diadema. Lepidoptera : two spp. sucking 
(Nos. 630, 634). — Fort Dauphin. 
Crotalaria humilis, E. Z. (Figs. 63-65.) 
In this species the tip of the carina and enclosed style 
are spirally twisted together, a further specialisation rendering 
the piston-action more complete. In other respects it agrees 
with C. capensis. Visitors : — Apis mellifica , ab. 
Psoralea deeumbens, Ait. 
The flower has an explosive mechanism : the staminal 
sheath having a distinct tendency to fly upwards, though the 
alae and carina have very little, if any, downward tension. 
Equilibrium is maintained by the vexillum which holds the 
alae together above the carina. The alae and carina are also 
united by, firsts a groove in the alae lying upon a slight 
