

| Aug. 31, 1871] 
better suited to the Biological Section, as it met with but little 
discussion among the geologists. This animal appears to have 
been a ruminant, about the size of an elephant, in some respects 
deer-like, in others more resembling the antelopes ; still stranger, 
it seems to have had some of the characteristic features of pachy- 
derms, the tapir for example. Dr. Murie showed that it was 
one of those radical forms which by some may be regarded as 
one of the progenitors of diverse herbivorous groups. The 
Sivatherium, according to him, was unlike all other living rumi- 
nants but one, the prongbuck, from the fact of its having had 
hollow horns, evidently subject to shedding. It differs thus from 
deer, whose solid horns anaually drop off, and from the antelope 
tribe, sheep, and oxen, whose hollow horns are persistent. Save 
one living form, the saiga, no recent ruminant possesses, as did 
the Svvatherium, a muzzle resembling in several ways the pro- 
boscis of the tapirs and elephants. Dr. Murie placed it in the 
family Antelocapridz, from which radiated the Bramatherium, 
the prong-buck, the saiga, tapir, and antelopes. 
The Relation of the Quaternary Mammalia to the Glacial 
Period was treated of by Mr. Boyd Dawkins, F.R.S. He 
divided the animals into five distinct groups, the first of which 
comprises those now living in the temperate regions of Europe 
and America, including the grizzly bear, the lynx, the bison, and 
the wild boar ; these animals bind the Quaternary to the existing 
fauna. The second group comprises those animals which are 
now confined to cold regions, as the glutton, the reindeer, the 
musk sheep, and the tailless hare: they constitute the Arctic 
division of Quaternary Mammalia, and imply a cold climate. 
The third group consists of those animals which are now only 
found in hot regions—the canichow, and hippopotamus ; and 
they indicated a hot climate, The only mode of getting over 
this discrepancy is to suppose that in those days the winter cold 
was very severe and the summer heat likewise very severe ; so 
that in the summer time the animals now found in warmer 
rezions migrated northwards, and in the winter time those now 
found in the Arctic regions went southwards. The fourth group 
consists of such extinct forms as the cave bear, the stag, the 
mammoth, and the woolly rhinoceros. The fifth group includes 
the sabre-tooth tiger, the Irish elk, AAinoceros megarhinus, and 
hemitechus, aod they, with some others, show that there is no 
great break between the Quaternary and the Pliocene, such as 
would warrant any sharply-defined division of great value. The 
interest centred more particularly in the Arctic group, and so far 
as the evidence went, it seemed to be extremely probable that 
they were in occupation of the areas in Great Britain in which 
they were found during the time the other areas, in which they 
were not found, were covered by glaciers ; and this period may 
be put down to that of the Jatest sojourn of the glaciers in the 
highest grounds of our islands, and even so far south as the dis- 
trict of the Avon. 
Prof. W. C. Williamson, F.R.S., read a paper On the Struc- 
ture of the Diploxylon, a plant of the Carboniferous Rocks. 
The Silurian Rocks of Selkirk and Roxburgh were treated ot 
by Messrs. Charles Lapworth and James Wilson. The authors 
pointed out that these rocks were capable of division into well- 
defined and well-marked groups. They had discovered a large 
number of fossils which had been obtained from all parts of the 
district ; from the lowest to the highest beds examined, and 
many of which were new to Scotland. For the purpose of com- 
parison the strata described were split up provisionally into five 
formations, namely :—1, The Hawick rocks; 2, The Selkirk 
rocks; 3, The Moffat series; 4, The Gala group; 5, The 
Riccarton beds. The Gala group they believed to be of Upper 
Bala or Caradoc age, and the Riccarton beds were classed with 
the Wenlock formation. 
~ Mr. Lapworth subsequently enumerated the graptolites of the 
Gala group, and described two new species. 
Two very important papers Ox Local Geology were communi- 
cated by Mr. D. J. Brown, Unfortunately from their being 
postponed until late in the day no time was allowed for their 
proper hearing or discussion. Mr. Brown endeavoured to show 
that the Silurian Rocks of the South of Scotland as developed 
in Dumfriesshire and Peeblesshire do not all belong to one 
geological epoch, as has been hitherto supposed, but that they 
belong to different periods—a lower one represented by the 
Moffat Rocks, well-known by their beds of Anthracite shales 
and Graptolites, and an upper series of later age, which lies 
unconformably on the Moffat rocks. These beds have been 
long known, and more recently they have been pointed out at 
Galashiels by Messrs, Lapworth and Wilson. Mr, Brown also 
NATURE 



355 
showed that in the Pentland Hills both the Wenlock and Lud- 
low divisions of the Silurian Rocks are represented, and that the 
lower Old Red sandstones formed no part of these beds : also that 
these Pentland beds are not the equivalent of the Lesmahago, 
but that these latter are a higher portion of the Ludlow than any 
found in the Pentlands. 
Mr. John Henderson described two sections across the Pent- 
land Hills, and showed that the Felstones cut through, indurate 
and enclose angular fragments of rocks belonging to the upper 
portion of the Lower Carboniferous formation, and that the so- 
called Old Red conglomerates contain limestone pebbles enclosing 
Carboniferous fossils, 

SECTION D. 
SUB-SECTION, —BOTANY 
Pror. DyEr, B.A., B.Sc., read a paper Ox the so-called 
“© Mimicry” in Plants. We said :—In all large natural families 
of plants there is a more or less distinctly observable general 
habit or facies, easily recognisable by the practised botanist, but 
not always as easily to be expressed in words. The existence of 
such a general habit in leguminous and composite plants is 
familiar to every one. What have been hitherto spoken of as 
numetic plants are simply cases where a plant belonging to 
one family puts on the habit characteristic of another. This 
is entirely different from mimicry among animals, inasmuch as 
the resembling plants are hardly ever found with those they 
resemble, but more usually in widely different regions. AZutisia 
speciosa from Western South America, a composite, has a scan- 
dent leguminous habit closely agreeing wih that of Lathyrus 
maritimus of the European shores. In the same way three 
different genera of ferns have species (found in distant parts 
of the world) indistinguishable in a barren state. The term 
Mimicry seems objectionable in these cases, and I propose 
Pseudomorphism as a substitute. As to the cause of the 
phenomenon, I can only suggest that the influence of similar 
external circumstances moulds plants into the similar form 
most advantageous to them. An illustration is afforded by 
the closely resembling bud scales which are found in widely 
separated natural orders of deciduous trees as modifications of 
stipules. I do not, however, think that the moulding influence 
need always be the same. J believe that different external con- 
ditions may produce the same result; in this respect they may 
be called analogous. Several identical plants are found on the 
seashore and also on mountains. ‘The reason is, [ believe, that 
they are equally able to tolerate the effect of soda salts and also 
of mountain climate ; the tolerance of either unfavourable con- 
dition gives them the advantage over less elastically constituted 
plants, and the two are therefore analogous in their effects. 
Professor Dyer’s paper gave rise to an interesting discussion, 
in which Profs Balfour, Dickson, Lawson, Perceval Wright, 
and Mr. Carruthers joined, in the course of which attention was 
called to the fact that while there might be ‘‘ pseudomorphs ” 
in the vegetable kingdom, yet there were also true cases of what 
is now technically called ‘‘ mimicry.” 
Dr. R. Brown read two papers Ox the Geographical Distri- 
bution of the Flora of North-West America, and On the Flora of 
Greenland. 1n the discussion on the latter paper Prof. Dickie 
stated that the Diatoms which he had catalogued for Dr. Brown 
had been for the most part obtained from the stomachs of mol- 
lusca. Prof. Lawson doubted if we knew more than just the 
coast flora of Greenland, all the mosses met with were just the 
commonest British species. Prof. Dyer alluded to the lack of 
positive knowledge that existed as to whether icebergs were or 
were not carriers of vegetable life. 
Mr. A. G. More exhibited some living plants of Sfivanthes 
gemmipara which had been collected by him in the last week in 
July, at Castletown, Berehaven. 
Prof, Balfour submitted some observations on the cultivation 
of ipecacuanha plants in the Edinburgh Botanic Garden for 
transmission to India. Asa curative for dysentery, the value of 
this plant was very great, and, in consequence of the partial 
failure, from various causes—such as the rashness and careless- 
ness of collectors—of its cultivation in its native country (South 
America), its cultivation here for sending out India became a 
matter of much importance. A short time ago Mr. James 
M‘Nab, of the Botanical Gardens, discovered that by making 
cuttings of the rhizome of the plant under the surface of the 
ground, numerous new shoots could be gat, and the plant so 
