40 Mr. 11. 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 tlie internode. I have found them in all the Orchi- 

 dacese that I have examined, but never in stems which are not 

 thickened, nor in the leaves*. 



Finally, a few observations on the aerial roots of the Orchi- 

 dacese. 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 

 line 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 being 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 aerial 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 

 fluids, like the spiral vessels. 



VI. — On the occurrence o/" Charadrius virginiacus, Borkh., at 

 Malta. By H. E. Strickland, M.A., F.G.S. 



I HARDLY know whcthcr 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 ll.II., whose 

 valuable papers on the birds of Corfu, Crete, Macedonia, and 



* Lindley remarked the existence of these tubercles in Oncidium aliis- 

 simum, in his * Introduction to Botany,' but gave no particular account of 

 them. — A. H. 



