62 



Fig. 5. — OAving to some uneven twisting of the caudicle the 

 pollinia have been deposited on the margin of the stigma. The 

 lateral appendages have prevented them from altogether going 

 astray, and pollination has been safelv effected. Lettering as in 



fig. 1. ; 



Fig. 6. — A very much magnified view of the two pollen-masses 

 (pj, of their caudicle (c), and disc (d). 



Plate VII. b. 

 Orthoceras strictum. 



Fig. 1. — The mature flower (natural size) from the front, show- 

 ing — Is, the lateral sepals; d s, the large hooded dorsal sepal, 

 enclosing the column and lateral petals; I, the labellum ; ov, the 

 ovary. 



Fig. 2. — Front view of column of an unpollinated flower (x6) 

 from the front, showing — a, anther; lap, lateral appendages of 

 the column; r, rostellum; s, stigmatic surface. 



Fig. 3. — The same column from the back showing a posterior 

 view of the same parts. 



Fig. 4. — A side view of the column of a flower that has just 

 expanded in which dehiscence of the anther is complete and the 

 rostellum is beginning to bend forward — ac, anther-case; other 

 lettering as in figs. 2 and 3. 



Fig. 5. — Front of the column after the adhesion of the pollinia 

 to the back of the stigma and collapse of the rostellum ; p, free 

 upper ends of pollen-masses; r, rostellum; s, stigma. 



Fig. 6. — Back view of column shown in the last figure. The 

 pollinia are free at their bases and upper ends, but attached in 

 their middle third. Lettering as in fig. 5. 



Fig. 7. — The pollinia, x6. The anterior surface is uppermost, 

 and shows the groove, along the middle third of which they after- 

 wards become attached to the back of the stigma. 



Plate VIII.a. 



Thelymitra antennifera. 



The various parts of the column are magnified by 4. 



Fig. 1. — Column of rather a young bud, showing the vertical 

 pollen-cases and smooth anther-point — s, stigma ; r, rostellum ; 

 p c, pollen-cases; id, column-wing; ap, anther-point; I ap, lateral 

 appendages. 



Fig. 2. — Column of more advanced bud. Note the increased 

 growth in width ; the commencing roughness of the anther-point ; 

 the obliquity of the pollen-cases. The lettering as in fig. 1. 



Fig. 3. — Column shortly before expansion of the flower, show- 

 ing oblique dehiscence of the pollen-cases ; the marked increase in 

 height of column drawing the cases away from the pollinia. Let- 

 tering as in fig. 1. 



Fig. 4. — Column just before expansion of flower^ showing the 

 increased roughness and the curving forward and downwards of the 

 anther-point, the tilting back of the lower ends of the pollen-cases, 

 and also the forcing backwards of the upper ends of the pollen 

 masses — p, pollen masses. Other lettering as in fig. 1. 



