250 THE ORCHID REVIEW. [AuGUST, 1909. 
Caladenia is another large and characteristic Australian genus, with 
spreading and often narrow sepals and petals—hence some of them are 
called ‘‘Spider Orchids”—and a broad recurved lip, which is usually 
densely studied with rows of papilla, and is attached at the base of the 
column by a slender elastic hinge, not unlike that of Bulbophyllum. 
Fitzgerald has recorded seeing a fly alight on the lip, which by the spring 
of the latter was thrown against the column, and on struggling to escape 
brought away the pollen masses and smeared them on the stigma. In 
another case a flower of C. dimorpha was pollinated in the same way by a 
house fly in an ordinary room, and Fitzgerald believes that some such large 
insects are the principal agents of fertilisation in the genus. If covered up 
the species fail to produce seed. 
Draka is a genus of four species of what are known as ‘‘ Hammer 
Orchids,” from the shape of the lip and the fact that it is attached to a long 
stalk. The blade of the lip trembles in the wind, but Fitzgerald could not 
make out the significance of the peculiar mechanism, “ unless,” he remarks, 
‘fit is useful as a decoy to insects from its resemblance to one in form and 
motion.’”’ Bauerlen, however, observes that in D. Hunteriana ‘‘at the 
slightest touch the labellum snatches across to the anther and stigma, 
subsequently returning with slowness to its remote position,” and the 
specific name of D. irritabilis was given by F. Mueller in reference to a 
similar property. 
Caleana is a genus of four species, closely allied to Draka, in which the- 
method of fertilisation was a mystery, but after long watching and 
examination was at last found out. The lip is uppermost, and is held in a 
state of unstable equilibrium by means of a narrow elastic hinge, while the 
column is expanded and forms a cup beneath. When an insect alights on 
the lip its weight brings down the column, and it is fairly caught in the cup, 
bringing away the pollen masses on escaping, when the lip again rights 
itself. These details were made out by experiment, but it is uncertain by 
what particular insect the flowers are normally fertilised. 7 
Thelynitra is another characteristic Australasian genus which shows 
evidence of degeneration, for some of the species are self-fertilised and in 
some cases the flowers fail to open, yet, Fitzgerald remarks, there is a 
viscid rostellum, and other structures adapted for cross-fertilisation are 
present, and in some cases the flowers are fertilised by insects. The perianth 
is regular, with six nearly equal segments, which are blue, purple, pink or 
yellow in the different species. The column wings are usually fringed or 
bear papilla, and in some cases they are stalked. There are upwards of 
thirty species. 
Some of the Diuridez have small and inconspicuous flowers, and thus it 
will be seen that a very wide range of diversity may be seen within the 
