468 MR. H. BOLUS’S CONTRIBUTIONS 
first of these, even were it rigidly confined to this group, I should 
regard it as too slight to be of generic value. Modifications of 
the rostellum are shown in the section of Disa referred to below, 
which I propose to call Vexillata, where it is prolonged behind 
into a fold beneath the anther. But besides this, there is a rudi- 
mentary third process, not so large nor so erect as in. Herschelia, 
in Disa obtusa, Lindl. ; and there are lateral tubercles, approach- 
ing those of Brownleea, in D. sp. (No. 4519 mihi). These facts 
show a tendency in the rostellum of Disa to variations which 
forbid our trusting to it alone for generic distinctions. With 
respect to the single gland of the pollinia, the remarks I am about 
to make respecting Monadenia wil show why I think that must 
also be abandoned. therefore propose to refer Herschelia again 
to Disa, of which it may be regarded as a section. 
-Monadenia was established by Lindley in 1838 as distinct from 
Disa by the single gland of its pollinia and its subequal fleshy 
petals. Most ofthe species have also the rostellum produced 
iuto lateral folds turning either forwards or backwards. In 
general habit they agree fairly well, and are somewhat different 
from the great majority of Disc. 
Mr. Bentham has admitted the genus with some apparent doubt, 
and in doing so has referred to a brief expression of my own in 
favour of its maintenance. Since that was written, I have exa- 
mined living specimens of Disa tenuis, Lindl.*, in which I found 
the single pollinary gland of Monodenia joined with all the re- 
maining characters of Disa, I have referred above to the uncer- 
tainty of characters derived from the rostellum ; and there remains 
nothing but habit, which is not unexceptional, for Disa bracteata, 
Sw.T (besides having fleshy lateral petals, and glands approximate 
though distinct), has almost entirely the appearance of a Mona- 
denia. Rather unwillingly, therefore, for the genus is already & 
large one and not easy to divide satisfactorily into groups, but, 
as it seems to me, quite unavoidably, I shall propose the union of 
* Lindley, working ona dried specimen, had not observed this. But Sonder, 
in his fuller description of D. leptostachys (Linnæa, xix. p. 98), which I have 
no doubt whatever is a synonym for the same plant [yes, certainly —N. E. 
Brown], says “ pollinia basi connata." 
t [The plant here intended is Disa cylindrica, Swartz (D. bracteata, Lindley, 
non Swartz), as I have compared Mr. Bolus’s specimen No. 4537 with Thun- 
berg's type-specimen of D. cylindrica !, which is undoubtedly also D. cylindrica, 
Swartz. ‘The D. bracteata of Swartz I have not seen; but from his brief 
description I believe it to be a very different plant. —N. E. Bnowx.] 
