species of the genus, throughout the tropics especially, probably covering more space than any two others. There are specimens from no less than fifty different stations and seventy collectors, preserved in the Hookerian Herbarium; its northern limit seems to be lat. 39°, where it is found in the Azores Islands, and its southern the Cape Colony; this, like several other very widely diffused species, does not inhabit the Australian continent, so far as I am aware. The following species should rank with it, — 2. L. pendulinum, Hook. (Ie. PI. t. 90). — 3. L.tortum, Sieber. — 4. L. densim, Lab. — 5.? L. dendroideum, Mich., this species is of rather dubious affinity and should perhaps be more properly placed in the Complauatum group, the branches being spread out in a flabellate manner, the whole frond very compressed or plane, and the leaves having a tendency to become bifarious; the latter are described as "being 4-6 fariously disposed, with those of the under surface smaller than the rest," (vid. Bot. Misc., vol. ii. p. 386), this is always the case, but at the same time those both on the upper and lower surface of the branches are appressed whilst the lateral spread, and the lower are often so small as to partake of the nature of stipules. All the species of the Cernuum group are robust in habit, erect, generally tall, copiously branched with their branches spreading on all sides; the spikes are sessile and very numerous, their mode of growth suffices to distinguish them from those of the Annotinum section.
The four groups above enumerated contain most of the imbricate-leaved species with uniform capsules arranged in terete spikes ; they are I believe strictly natural, though all are not founded upon characters of equal value. One species, more nearly allied to some of the above than to any of the other great divisions of the genus, stands very much by itself, the L. iaterale, Br. (Mr. Brown's L. diffusion being possibly a variety of it), in which the spikes are placed upon such very short branches as to appear truly lateral ; in this respect, as in their obscurely angular form, it approaches some of the distichous-leaved group, but the habit is totally dissimilar and the foliage like that of L. inundatum, var. Alopecuroides.
3. Lycopodium varlum, Brown, Prodr. p. 165 et auctorum. L. pachystachyon, Desv. Encycl. Meth. Sujijil. vol. iii. p. 5-44.
Hab. Lord Auckland's group and Campbell's Island ; very common in the woods.
Under the former species I enumerated the different groups into which those of tins genus with leaves imbricated round the stem and terete spikes arranged themselves ; they forai, together, one of the large primary divisions of Lycopodium ; they are inhabitants of the cold as well as of the tropical parts of the globe, generally assuming, as they approach the. equator, a larger growth and more robust habit, both the individual species peculiar to the low latitudes, and the varieties of those which equally inhabit the polar regions, being more fully developed within or near the tropics. There they are not replaced by the distichous-leaved group, but under most conditions are equally abundant with them. Throughout all changes of temperature and varieties of exposure, the scales of the spike never exhibit any tendency to become foliaceous, nor do they possess capsules in the axils of the leaves.
There are, however, other Lycopodia whose fructifications are as manifestly spicate as the last, and which accompany them through all climates, but whose spikes are angular and the scales not materially different from the cauline leaves; these, in passing from a temperate to a warmer parallel, gradually lose their spicate character, the capsides appear equally in the axils of the upper leaves and in the spikes, the latter become gradually reduced and at length obliterated, when the fructifications are wholly axillary: under excessive heat and moisture, the same effect is produced by the prolongation of the axis beyond the apex of the spike, into a leafy branch, similar to the lower parts of the stem, and at the same time the conversion of the scales into ordinary leaves. A third modification is presented in those whose spikes divide or branch. Here there is a blending of the two divisions Selago and Phlegmaria, through L. varitim and its allies, which together, I consider to form one natural group ; and it is further to be remarked, with regard to them all, that these modifications of the inflorescence are not only the effects of latitude and climate, but that one species seems to assume all these appearances in a single locality, which in other parts of the globe is invariable through a considerable area ; and that the causes of the change
