Chap. VIII. FLOWERS OF ORCHIDS. 243 



ill Cypripedium, and in other cases are generally 

 represented either by membranous expansions, or by 

 minute auricles without spiral vessels. These auricles, 

 however, are sometimes quite absent, as in some species 

 of Ophrys. 



On this view of the homologies of Orchid-flowers, 

 we can understand the existence of the conspicuous 

 central column, — the large size, generally tripartite 

 form, and peculiar manner of attachment of the la- 

 bellum, — the origin of the clinandrum, — the relative 

 position of the single fertile anther in most of the 

 genera, and of the two fertile anthers in Cypripedium, 

 — the position of the rostellum, as well as of all the 

 other organs, — and lastly, the frequent occurrence of a 

 bilobed stigma, and the occasional occurrence of two 

 distinct stigmas. I have encountered only one case oi 

 dijQficulty, namely in Habenaria and the allied genus, 

 Bonatea. These flowers have undergone such an 

 extraordinary amount of distortion, owing to the wide 

 separation of their anther-cells and of the two viscid 

 discs of the rostellum, that any anomaly in them is 

 the less surprising. The anomaly relates only to the 

 vessels supplying the sides of the upper sepal and 

 of the two upper petals ; for the vessels running into 

 their midribs and into all the other more important 

 organs pursue the same identical course as in the other 

 Ophrese. The vessels which supply the sides of the 

 upper sepal, instead of uniting with the midrib and 

 entering the posterior ovarian group, diverge and enter 

 the postero-lateral groups. Again, the vessels on the 

 anterior side of the two upper petals, instead of uniting 

 with those of the midrib and entering the postero- 

 lateral ovarian groups, diverge, or wander from their 

 proper course, and enter the antero-lateral groups. 



This auomaly is so far of iuiportance, as it throws 



