124 DR. D. LYALL ON THE BOTANY 
of two paleæ, placed directly opposite one another, and quite resem- 
bling in form and appearance the ordinary outer palea. Within 
these, and at right angles to them, are two more segments, precisely 
resembling the inner pales of the natural flower; within these, 
again, are à number of thin membranous scales, some of them 
having more or less of the appearance of the stigmata. 
Thus in these very curious specimens the following changes, or 
some of them, may be observed :— 
lst. An alteration in the form of the spikelets, whereby they 
become spheroidal. 
2ndly. Their arrangement in pairs instead of singly on each 
notch of the rachis, and also in more than two vertical rows. 
3rdly. The disposition of the florets in close tufts or whorls; in 
consequence of which, 4thly, the outer and inner pale: become 
more or less fused together. 
5Sthly. Multiplication of the inner portions of these florets, 
and their presence in the form of scales, exhibiting transitional 
stages between the scales and stamens. 
6thly. Bifurcation of the axis of the spikelet; and, 7thly, the 
occasional presence of a floret of peculiar construction in the 
angle of divergence of the two branches. 
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Account of the Botanical Collections made by Davrp DfALL, 
M.D., R.N., F.L.S., Surgeon and Naturalist to the North 
American Boundary Commission. 
[Read June 18, 1863.] 
Tux plants upon which the following observations were made, and 
of which a complete systematic catalogue is appended, were col- 
lected in the years 1858-1861, during which period I was, firstly, 
Surgeon of H.M. Surveying-ship ‘ Plumper,’ and afterwards Sur- 
geon and Naturalist to the Commission appointed to mark out 
the boundary-line between the British Possessions and those of 
the United States of America, to the westward of the Rocky 
Mountains. 
The dried plants were transmitted from time to time, as collected 
and preserved, to Sir William Hooker, at the Royal Gardens at 
Kew. Of these, the earlier collections were provisionally arranged 
and catalogued soon after their arrival by Mr. Black, the Curator 
of the Herbarium; my later and more extensive collections, to- 
