Chap. Vn. MOEMODES IGNEA. 211 



of the pollinium. This gorged condition may perhaps ' 

 facilitate the rupture of the hinge. 



The pollinium does not differ much from that of 

 Oatasetam (see fig. 29, D, p. 183); and it lies in like 

 manner curved round the rostellum, which is less protu- 

 berant than in that genus. The upper and broad end of 

 the pedicel, however, extends beneath the pollen-masses 

 within the anther ; and these are attached by rather 

 weak caudicles to a medial crest on its upper surface. 



The viscid surface of the large disc lies in contact 

 with the roof of the stigmatic cavity, so that it cannot 

 be touched by an insect visiting the flower. The 

 anterior end of the disc is furnished with a small de- 

 pendent curtain (dimly shown in fig. 32) ; and this, 

 before the act of ejection, is continuously joined on 

 each side to the upper margins of the stigmatic cavity. 

 The pedicel is united to the posterior end of the disc ; 

 but when the disc is freed, the lowermost part of the 

 pedicel becomes doubly bent, so that it then appears 

 as if attached by a hinge to the centre of the disc. 



The labellum is a highly remarkable structure : it 

 is narrowed at its base into a nearly cylindrical foot- 

 stalk, and its sides are so much reflexed as almost to 

 meet at the back, forming a folded crest on the sum- 

 mit of the flower. After rising up perpendicularly 

 it arches over the apex of the column, against which it 

 is firmly pressed down. The labellum at this point is 

 hollowed out (even in the bud) into a slight cavity, 

 which receives the bent summit of the column. This 

 slight depression manifestly represents the large cavity, 

 with thick fleshy walls, which insects gnaw, on the 

 anterior surface of the labellum in the several species 

 of Catasetum. Here by a singular change of function, 

 the cavity serves to keep the labellum in its proper 

 position on the summit of the column, but is, perhaps. 



