534 THE FERTILISATION OF FLOWERS. [parr ut. 
become attached to the base of the proboscis, as Darwin observed 
in the case of Agrotis segetum and Anaitis plagiata+ 
Professor Asa Gray has published most interesting observations 
on the structure and mode of fertilisation of certain American 
species of Platanthera (273, 274, 277). 
Himantoglossum hircinwm, Rich—Hildebrand saw this species 
visited by a bee (361). 
Gymnadenia conopsea, R. Br—The spur is so narrow that the 
honey is only accessible to Lepidoptera. George Darwin observed 
the flower to be visited by nocturnal Lepidoptera (Plusia chrysitis, 
P. gamma, Anaitis plagiata, Triphana pronuba). On the Alps, 
T have seen this species visited by twenty-seven different species 
of Lepidoptera, mostly butterflies (600, fig. 13). 
Gymnadenia odoratissima, Rich., has a much shorter spur 
(4 or 5 mm., against 13 or 14 mm. in G. conopsea), paler colour, 
and stronger and more aromatic perfume. I have only found it 
visited by three species of nocturnal Lepidoptera (609, fig. 13). 
Nigritella angustifolia, Rich.—The ovary is not twisted, and the 
position of the parts of the flower is, therefore, the reverse of that 
in Gymnadenia. Its strong odour of vanilla attracts very numerous 
Lepidoptera (I observed forty-eight species), to the under side of 
whose proboscis the pollinia get cemented (609, fig. 15). 
Nigritella suaveolens, Koch., seems to be a hybrid between JN. 
angustifolia and Gymnadenia odoratissima; but as G. odoratissima 
cements its pollinia to the upper side of the insect’s proboscis, and 
NV. angustifolia to the lower, it is difficult to see how this hybrid 
can be produced, except from flowers of the species which are already 
abnormally inclined. Such abnormally placed flowers, are, however, 
to be met with now and then in both species, (609, fig. 16). 
Anacamptis pyramidalis, Rich—The flower agrees in most 
points with the species of Orchis to be described immediately, and 
like them secretes no free honey. The spur is very narrow, only 
admitting the tongues of Lepidoptera, and the mode of attachment 
of the pollinia by means of a saddle-shaped band instead of two 
round disks is also specially fitted for the proboscis of Lepidoptera. 
Darwin observed twenty-three different species of butterflies and 
moths carrying pollinia of A. pyramidalis on their tongues. 
Ophrys muscifera, Huds.—This species seems to be adapted 
for carrion-loving Diptera. The flies are probably attracted by 
the dark purple under lip, which bears a pale blue smooth spot, 
 T have given an account of the flower of Platanthera bifolia, Rich., with figures, 
in No. 589 and No, 609, 
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