174 THE VICTORIAN NATURALIST. 



rivers existed during the volcanic period, and easily cut channels 

 through the loose ejectamenta, which time and weathering have 

 modified into their present state. 



Finally, with regard to the vegetation of this period. It is 

 probably buried in the form of thin coal seams or carbonaceous 

 material. Leaf impressions have been found in similar deposits 

 in other parts of Australia and in Tasmania, attributable, I 

 believe, to the same volcanic period, but none in the desert 

 sandstone. It may be, however, that fossils of the ancient flora 

 may yet be found at the base of the sandstone ; but I do not 

 anticipate that such vegetable remains will be very numerous in 

 Arnhem's Land, as the conditions favourable to their preservation 

 seem to have been absent. 



The foregoing epitome of the geology of Arnhem's Land I 

 have purposely made very brief, to meet the requirements of 

 the space at the disposal of the Field Naturalists' Club. The 

 facts here stated have not, however^ been previously placed 

 before the public. It forms the briefest possible account of the 

 geology of North Australia, which, though discovered nearly 

 300 years ago, has only lately been explored. 



DESCRIPTION OF A NEW FORM OF THE ORCHID- 

 GENUS DRAK^A, INDIGENOUS TO NEW SOUTH 

 WALES AND VICTORIA. 



By Baron Von Mueller, K.C.M.G,, M. & Ph. D., F.R.S. 



DRAKiEA HUNTIANA. 



Leafless at flowering time ; empty bracts, two ; flowers three 

 or two ; stalklets much longer than the floral bracts ; all three 

 calyx-lobes about as long as the pair of petals, reflexed, some- 

 what shorter than the prolongation of the gynostemium ; petals 

 linear-elliptical ; stalk-like portion of the labellum almost longer 

 than the horizontal portion ; the latter glandular-bilobed at the 

 lower end, beset with purplish hairlets at and towards the middle, 

 extended at the upper end into a fringed comparatively long 

 membrane ; gynostemium provided at and below its summit with 

 opposite semilanceolar membranous much pointed appendages ; 

 fruit narrow-eUipsoid. 



Between loose stones on Mount Tingiringi, at an elevation of 

 about 5,000 feet (W. Baeuerlen). 



In our present state of knowledge, concerning specific demar- 

 cations, this plant cannot be considered conspecific with Z). 

 irritabilis, because that plant, from all its hitherto known 

 localities, has very short flower stalklets, unequal calyx-lobes, 

 very narrow petals, a much shorter protraction of the gynos- 

 temium and an unfringed appendage of the labellum. 



