Chap. II. rLATANTHERA. 75 



I felt convinced, from the position of the viscid discs, 

 that it would be fertilised in a different manner from 

 the Larger Butterfly Orchis; and now, owing to the 

 kindness of Mr. F. Bond, I have examined two moths, 

 namely, Agrotis segetum and Anaitis plagiata, one with 

 three pollinia, and the other with five pollinia, attached, 

 not to the eyes and side of the face as in the last 

 species, but to the base of the proboscis. I may 

 remark that the pollinia of these two species of Habe- 

 naria, when attached to moths, can be distinguished at 

 a glance. 



Professor Asa Gray has described* the structure of 

 no less than ten American species of Platanthera. 

 jMost of them reseml^le in their manner of fertilisation 

 the two British species ; but some of the species, in 

 which the viscid discs do not stand far apart, have 

 curious contrivances, such as a channelled labellum, 

 lateral shields, &c., compelling moths to insert their 

 proboscides directly in front. P. hooJceri, on the other 

 hand, differs in a very interesting manner : the two 

 viscid discs stand widely separated from each other ; 

 consequently a moth, unless of gigantic size, would be 

 able to suck the copious nectar without touching either 

 disc ; but this risk is avoided in the following manner : 

 — the central line of the stigma is prominent, and the 

 labellum, instead of hanging down, as in most of the 

 other species, is curved upwards, so that the front of 

 the flower is made somewhat tubular and is divided 

 into halves. Thus a moth is compelled to go to the 

 one or other side, and its face will almost certainly be 

 brought into contact with one of the discs. The drum 

 of the poUinium, when removed, contracts in tlie 

 same manner as I have described under P. chlorantha. 



♦'American Journal of Science,' vol. xxxiv. 18G2, pp. 113, 25f), 

 and 424, and vol. xxxvi. 1S63, p. 292. 



