88 
NATURE 
| Fune 2, 1870 
period seem to have been few, and of small dimensions in 
comparison with those of the coal. __ 
Rising still higher in the vegetable kingdom, and arriv- 
ing at unquestionable Gymnosperms, we find in the De- 
vonian of Eastern America, and also, I believe, in that of 
Scotland and Germany, trunks which may be referred to 
Coniferze. In the Middle and Upper Devonian these 
present the structure of modern Araucarian pines, or that 
modification of it belonging to the Carboniferous trees of 
the genus Dadoxylon. In the Lower Devonian we have 
what seems to be a simplification of the Coniferous struc- 
ture, in the cylindrical wood-cells, marked only with spiral 
threads, found in the genus Profofaxites. These trees 
are very abundant as drift trunks in the Lower Devonian, 
down almost to its bottom beds, and sometimes attain to 
a diameter of three feet. Though of a structure so lax 
that itis comparable only with the youngest stems of 
ordinary Coniferae, these trees must have been durable, 
and they are furnished both with medullary rays and rings 
of annual growth. Unfortunately we know nothing of 
their foliage orfruit. Fig. 4 represents a fragment of the 
wood of one of these trees, mineralised by infiltration of 
the tissues with silica, so that the structure is preserved, 
But for one little fragment of wood, we should have had 
no indication of the existence in the Erian of any trees 
of higher organisation than the Conifers. This fragment, 
found by Professor Hall at Eighteen-mile Creek, Lake 
Erie, has the dotted vessels characteristic of ordinary 
Exogens, and unquestionably indicates a plant of the 
highest kind of organisation. Until confirmed by other 
facts, this discovery may be received with doubt, but I 
believe it can be relied on, 
Our knowledge of the flora of the Upper Silurian is at 
present nearly in the same state with that of the Middle 
and Lower Devonian ten years ago. I knowin the Upper 
Silurian of Canada but two species of Psz/ophyton, both 
apparently identical with Devonian forms. In England, 
besides the spore-cases known by the generic name 
Pachytheca, there exist in the collections of the Geological 
Survey fragments of wood and bark which I believe 
indicate two additional species. In Germany three or 
four species are known in rocks of this age. All of these 
plants appear to be Acrogens allied to Lycopodiacez. 
That these few species constitute the whole flora of the 
Upper Silurian we can scarcely believe. They occur in 
marine formations, and were probably drifted far from the 
somewhat limited land-surfaces which existed in the 
explored parts of the Upper Silurian areas. When we 
obtain access to deposits of this age formed in shallows 
or estuaries, we may hope to find a flora of greater rich- 
ness ; and, judging from present indications, not dissimilar 
from that of the Lower Devonian. 
With the exception of some remains which I believe 
to be of very doubtful character, the Lower Silurian has 
as yet afforded no remains of land plants, and in North 
America, at least, this is very significant, inasmuch as we 
have, in the Potsdam sandstone, extensive sandy flats of 
this period, in which we might-expect to find drifted 
trunks of trees, if such had existed. But the search is 
not hopeless, and we may yet find some estuary deposit 
on the margin of the ancient Laurentian continent, in 
whose beds the plants of that old land may occur. 
Lastly, for reasons stated in a paper lately published in 
the Proceedings of the Geological Society, I believe that 
the extensive deposits of graphite, which exist in the 
Laurentian of Canada, are of vegetable origin, and 
possibly in part produced by land plants, as yet altogether 
unknown to us. If the Paleozoic was the age of 
Acrogens, the Eozoic may have been that of Anophytes and 
Thallophytes. Its plants may have consisted of gigantic 
mosses and lichens, presenting us with a phase of 
vegetable existence bearing the same relation to that of 
the Paleozoic, which the latter bears to that of more 
modern periods. But there is another and a more startling 
possibility, that the Laurentian may have been the period 
when vegetable life culminated on our planet, and existed 
in its highest and grandest forms, before it was brought 
into subordination to the higher life of the animal. The 
solution of these questions belongs to the future of 
geology, and opens up avenues not merely for speculation 
but also for practical work, 
The aboye must be regarded as merely a sketch of the 
present aspect of the subject to which it relates. Details 
must be sought elsewhere, J. W. Dawson 
NOTES 
Tue Royal Commission on Scientific Instruction and the 
Advancement of Science has already begun work. A second 
meeting was held on the 31st ult. at Devonshire House. Present: 
The Duke of Devonshire, K.G., chairman; the Marquis of 
Lanslowne ; Sir J. Lubbock, Bart., M.P., F.R.S.; Sir]. P. 
Kay Shuttleworth, Bart. ; Mr. B. Samuelson, M.P.; Dr, Sharpey, 
Sec. R.S. ; Professor Huxley, F.R.S.; Dr. W. A. Miller, 
Treas. R.S.; and the secretary, Mr. J. Norman Lockyer, F,R.S, 
A MEETING of the Syndicate appointed to consider the ways 
and means of establishing a Chair of Experimental Physics at 
Cambridge was held on Tuesday last. 
We may remind our Astronomical readers that the Visitation 
of the Royal Observatory at Greenwich takes place at 3 P.M, on 
Saturday. ; 
THE annual meeting for the elec‘ion of Fellows into the 
Royal Society was held this morning, 
THe Geographical Society of Paris has bestowed a well- 
earned honour on our countryman, Mr. Alfred R, Wallace, by 
awarding him one of their gold medals for his researches in the 
Malay Archipelago. 
Av the meeting of the French Academy, held on the 23rd 
ult,, the following list of candidates for the place vacant by the 
death of Professor Magnus was presented by the Secret Com- 
mittee ;—1, Mr. Joule, 2, MM. Angstrém, Billet, Dove, Groye, 
Henry, Jacobi, Lloyd, Riess, Stokes, Tyndall, Volpicelli, and 
Sir William Thomson, 
Tur Gresham lectures for the present week at the Gresham 
College, Basinghall Street, are by Dr. Symes Thompson, on the 
2nd, 3rd, and 4th of June, at 7 P.M., on ‘“‘The Epidemics 
of the Middle Ages,” on ‘‘Sedatives,” and on “ Narcotics.” 
They are free to the public, and will be illustrated with diagrams, 
tables, and chemical experiments, 
THE municipal administration of Paris has decided on pub- 
lishing a series of documents on the history of the capital. The 
commission appointed for this purpose has placed at the head of 
its programme a sketch of the pre-historic epochs, and has 
entrusted this labour to M. Belgrand, who is well known in the 
scientific world by his important works on the basin of Paris, 
In presenting to the Academy a résumé of his work, he divides 
it into four parts—the diluyian epoch, the great water-courses of 
the age of stone, the history of the peat-mosses, and the palaon- 
tological history of the basin of the Seine during the quaternary 
epoch, Our Common Council of London has a splendid oppor- 
tunity of distinguishing itself in the same way; is it too much 
to expect of such an august body? 
WE perceiye with great pleasure that the Radcliffe Library at 
Oxford is being adapted more completely to the wants of students 
of science, Students in any department of natural knowledge, 
who need scientific works, maps, or plans which they do not 
find in the library, are invited to record their wants in a book 
kept forthe purpose. There is a standard microscope, by Powell 
and Lealand, attached to the library, for the comparison of 
objects with the illustrated works of the library. : 
