Chap. I. OKCHIS PTEAMIDALIS. 17 



which I have examined, and whioh is ranked by several 

 botanists as a distinct genus. The relative position of 

 the parts (fig. 3) is here considerably different from 

 what it is in 0. masoula and its allies. There are two 

 quite distinct rounded stigmatic surfaces (s, s, A) 

 placed on each side of the pouch-formed rostellum. 

 This latter organ, instead of standing some height 

 above the nectary, is brought down (see side view B) 

 so as to overhang and partially to close its orifice. 

 The ante-chamber to the nectary, formed by the 

 union of the edges of the labellum to the column, 

 which is large in 0. masoula and its allies, is here 

 small. The pouch-formed rostellum is hollowed out 

 on the under side in the middle : it is filled with 

 fluid. The viscid disc is single and of the shape of a 

 saddle (figs. C and E) ; it carries on its nearly flat 

 top or seat the two caudicles of the poUinia, the ends 

 of which firmly adhere to its upper surface. Before 

 the membrane of the rostellum ruptures, the saddle- 

 formed disc can be clearly seen to ba continuous with 

 the rest of the surface. The disc h partially hidden 

 and kept damp (which is of great importance) by the 

 over-folding bases of the two anther-cells. It consists 

 of several layers of minute cells, and is therefore rather 

 thick ; it is lined beneath with a layer of highly ad- 

 hesive matter, which is formed within the rostellum. 

 It corresponds strictly to the two minute, oval, sepa- 

 rate discs to which the two caudicles of 0. masoula 

 and its allies are attached. 



When the flower opens and the rostellum has 

 become symmetrically ruptured, either from a touch 

 or spontaneously (I know not which), the slightest 

 pressure depresses the lip, that is, the lower and bi- 

 lobed portion of the exterior membrane of the ros- 

 tellum, which projects into the mouth of the nectary. 



