40 Mr. H. E. Strickland on the occurrence of 
nular mass, which however is sometimes absent. They stand on 
all sides of the tubes, both toward the axis and toward the pe- 
riphery of the internode. I have found them in all the Orchi- 
daceze that I have examined, but never in stems which are not 
thickened, nor in the leaves*. 
Finally, a few observations on the aérial roots of the Orehi- 
dacee. They seldom pass into the earth, even when this is 
placed in their way ; they grow on long and freely in the air, nay 
sometimes in an upward direction. Only to the cracked bark of 
trees, to which the plants are attached, they adhere by means of 
fine hairs. Meyen observed that the outer layer of these roots 
is composed of spiral cells, and this layer is of tolerable thick- 
ness. This is succeeded by a rather lax parenchyma, but in the 
vicinity of the ligneous nucleus, as I will temporarily call it, 
scattered spiral cells occur again, their convolutions bemg more 
lax. The ligneous nucleus is composed, as in the roots of all 
Monocotyledons, of one or more circles of vascular bundles, in a 
parenchyma of narrow cells, which are narrower than in the rind, 
and therefore form no true pith. In the hairs a delicate spiral 
fibre is rolled up in close convolutions, but the base is expanded 
and devoid of spiral fibres, although spiral cells lie beneath. 
Moreover these hairs, like all radical hairs, have no transverse 
septa. The occurrence of abundance of spiral cells directly in 
these aérial roots, which very seldom descend into the earth, may 
contribute to the discovery of the at present enigmatical function 
of these cells, since they never absorb nor carry onward coloured 
tiuids, like the spiral vessels. 
VI.—On the occurrence of Charadrius virginiacus, Borkh., at 
Malta. By H. E. Srricxzanp, M.A., F.G.S. 
I narpty know whether the occurrence of a new or unrecorded 
species of bird at Malta is to be regarded as forming an addition 
to the European fauna, because geographers are I believe not yet 
agreed as to whether Malta belongs to Europe or to Africa. But 
in either case the discovery of Charadrius virginiacus at Malta is 
not the less interesting, for this species has not as yet, I believe, 
been noticed in either of those two quarters of the globe to which 
that island is intermediate. 
I have lately found an accidentally mislaid letter, addressed 
to me in 1846 by Capt. H. M. Drummond, 42nd R.H., whose 
valuable papers on the birds of Corfu, Crete, Macedonia, and 
* Lindley remarked the existence of these tubercles in Oncidium altis- 
simum, in his ‘ Introduction to Botany,’ but gave no particular account of 
them.—A. H. 
