78 
NATURE 
| May 25, 1871 

the distribution in time of some of the earlier genera of trilo- 
bites, it would appear that the genus O/enus is represented in 
Britain and Europe by twenty-two species, confined to the 
Lingula-flags and Tremadoc rocks, and not occurring so low as the 
Menevian group. The absence of this genus from the Menevian 
group, and its occurrence throughout the whole of the Lingula- 
flags, and in the Tremadoc rocks, along with the fact that 
so far as present observations go, no species of Paradoxides 
ranges higher than the Menevian group, have afforded 
good palontological grounds for placing the line of de- 
marcation between Upper and Lower Cambrian at this 
spot, and for including the Menevian group in the Lower 
Cambrian, to the bulk of which it is intimately united paleonto- 
logically. Mr. Hughes bore testimony to the admirable work 
done by Mr. Hicks, who had, almost unaided, worked out the 
geology of that district. Allowing that many subdivisions and 
new specific names had with great advantage been introduced into 
petrology, he defended the Survey nomenclature by reference to 
the then received definition of syenite and greenstone, terms still 
perfectly understood and applicable to the main mass of the 
rocks in question, though possibly subsequent closer examination 
and new sections may have rendered some modification of the 
boundary lines desirable. He was prepared to allow the meta- 
morphic origin of all rocks of the classes under consideration, 
but did not think there was sufficient evidence to show that the 
divisional planes in the syenite and greenstones of St. David’s 
were due to original stratification, but might correspond rather 
to the great joints of most granites. Mr. Hughes pointed out 
that the conglomerate contained fragments of the hornstone and 
quartz of this older series, which he considered was probably 
part of an old ridge or shoal, possibly of Laurentian, but cer- 
tainly of Pre-Cambrian age, and thought that there were slight 
differences in the lithological character of the beds on either side, 
such as might be explained on this supposition. He agreed with 
Prof. Ramsay in thinking that there was evidence of the proximity 
of land in early Cambrian times, but was not prepared to refer these 
red rocks to inland seas or lakes as opposed to open sea ; the whole 
seemedratherthedeposit ofan open sea encroaching during submer- 
gence. He did not attach very much importance to the restric- 
tion of genera to limited horizons in these older rocks of St. 
Dayid’s. For, as it was reserved for Dr. Hicks to discover these 
fossils after somany other observers had examined the district, 
he anticipated that further researches must certainly result in 
finding links which will connect together more closely beds, the 
stratigraphical relations of which seem to indicate so clearly an 
unbroken though varying series. Mr. Gwyn Jeffreys had been 
struck by the intercalation of non-fossiliferous beds from time to 
time among the fossiliferous beds described in the paper. This 
was the case in beds now in course of formation, and appeared 
to arise from the great deposits of mud brought down by rivers 
and redeposited in certain positions in the sea-bed. That this 
was the case had been proved by recent dredging operations both 
in the Atlantic, off Spain, and in the Mediterranean. Mr. Boyd 
Dawkins called attention to the gap which had been filled by the 
discoveries recorded in the paper, inasmuch as the Molluscan, 
Annelid, and Crustacean forms were now carried back far into 
the Cambrian period, and yet without any trace of their conver- 
gence, so that the origin of life might be as far removed from 
that period as was the Cambrian from the present time. The 
difference in the colours of the rocks he was inclined to refer to 
the different degrees of oxidisation of the iron they contained, 
which might supervene in a comparatively short time. The Rey. 
W. S. Symonds had, in visiting the spot, been much struck by 
the rocks, at that time termed syenite, which he believed might 
be an extension ef those on the Carnarvonshire peninsula, and 
which he thought supported the whole series of the Cambrian 
rocks, so that they might after all be the Laurentian, the same as 
those of Sutherlandshire and Assynt. If this were the case the 
nomenclature of the Geological Survey would have to be altered, 
and the rocks of Pistyl and Holyhead no longer termed meta- 
morphosed Cambrian rocks, but Laurentian. Mr. Hicks, in 
reply, stated that the quartziferous breccias forming the central 
ridge contained so many rolled pebbles, and were, moreover, in 
places so distinctly bedded, that there could be no doubt of their 
being sedimentary. Other beds, described as greenstone in the 
maps of the Geological Survey, were also distinctly laminated. 
The non-occurrence of fossils in the more sandy beds he attributed 
to their having been deposited in very shallow water. The fossils 
occurred principally in fine-grained beds of a flaggy nature. 
**On the Age of the Nubian Sandstone,” by Mr, Ralph Tate, 

F.G.S. The author remarked that the sandstone strata underlying 
the Cretaceous limestones, and resting upon the granitic and 
schistose rocks of Sinai, had been identified with the ‘** Nubian 
Sandstone” described by Russegger as occurring in Egypt, 
Nubia, and Arabia Petrzea. In the absence of palzontological 
evidence, this sandstone has been referred to the Mesozoic group, 
having been regarded by Russegger as Lower Cretaceous, and by 
Mr. Bauerman and Figari-Bey as Triassic, the latter considering 
an intercalated limestone bed to be the equivalent of the Muschel- 
kalk. The author has detected Orthis Michelinit ina block of 
this limestone from Wady-Nasb, which leads him to refer it to 
the Carboniferous epoch, as had already been done by the late 
Mr. Salter from his interpretation of certain encrinite-stems 
obtained from it. The author mentioned other fossils obtained 
from this limestone, and also referred to the species of Lepido- 
dendron and Sigillaria derived from the sandstone of the same 
locality. He regarded the Adigrat Sandstone of Mr. Blanford 
as identical with the Nubian Sandstone.—3. ‘“‘On the Dis- 
covery of the Glutton (Gz/o /uscus) in Britain,” by Mr. W. Boyd 
Dawkins, M.A., F.R.S. The author in this paper de- 
scribed a lower jaw of the Glutton, which had been obtained by 
Messrs. Hughes and Heaton froma cave at Plas Heaton, where 
it was associated with remains of the wolf, bison, reindeer, 
horse, and cave-bear. He remarked that he could detect no 
specific difference between the Gudo sfeleus Goldfuss, from 
Germany, and the living Gu/o Jduscus, except that the 
fossil Carnivore was larger than the living, probably from the 
comparative leniency of the competition for life in postglacial 
times. He referred to the distribution of the Glutton in a fossil 
state, and argued that its association with the reindeer, the 
marmot, and the musk-sheep would imply that the postglacial 
winters were of Arctic seyerity, whilst the presence of remains of 
the hippopotamus, associated with the same group of animals, 
would indicate a hot summer, such as prevails on the Lower 
Volga. Mr. Hughes indicated the exact position in which the 
jaw of the glutton was found, but pointed out that, owing to the 
excavations of keepers, badgers, rabbits, &c., the earth was so 
much disturbed in that part that it was impossible to be sure of 
the original relative position of the bones. He showed that the 
Plas Heaton Cave was on a hill rising from the top of the plateau, 
while the Cefn, Brysgill, and Galltfeenan Caves were in the 
gorge cut through that plateau, and therefore that the Plas Hea- 
ton Cave was probably formed, and might possibly have been 
first occupied, at a much earlier period than the others. As it 
appeared to pass under that part of the hill which is overlapped 
by heavy drift, he thought it quite possible that this may have 
been a preglacial cave, and that by and by we may find evidence 
of preglacial fauna in it, The Rey. W. S. Symonds mentioned 
that in some of the pot holes in the roof of the Cefn Cave he had 
procured silt containing remains of shells determined by Mr. 
Jeffreys to be marine. Mr. Hughes explained that these shells 
had probably been washed in from the superficial drift of the 
district. Mr. Dawkins, in reply, expressed his belief that 
though the excavation of the caves in question might have taken 
place at different periods, yet that their occupation was, geologi- 
cally speaking, contemporaneous, 
Mathematical Society, May 11.—Mr. W. Spottiswoode, 
president, in thechair. Mr. C. J. Monro, B.A., late Fellow of 
Trinity College, Cambridge, was elected a member ; and Mr. J. 
Griffiths, M.A., Fellow of Jesus College, Oxford, was proposed 
for election. The Hon. J. W. Strutt, fellow of Trinity College, 
Cambridge, was admitted into the Society. Prof. Henrici indi- 
cated the method of treatment he had employed in his paper 
**On the Singularities of the Envelopes of a non-unicursal Series 
of Curves.” Mr. Strutt then read his paper “ On the Resultant 
of a large Number of Vibrations of irregular phase, as applied 
to the explanation of Coronas.” Sir W. Thomson, Prof. Clerk 
Maxwell, and Mr. Strutt made some further remarks on the sub- 
ject of the paper. Mr. Maxwell then gave a description of two 
solar halos he had recently seen, and Prof. W. G. Adams gaye 
some additional particulars in the case of one of the phenomena 
which had also been noticed by himself. Prof. Cayley then 
communicated an account of a paper by Mr. J. Griffiths ‘On 
the problem of finding the circle which cuts three given 
circles at given angles.” The president next requested assistance 
in the solution of a ‘Question on the Mathematical Theory of 
Vibrating Strings,” which he had been unsuccessful in solving. 
Mr. Strutt mentioned some results he had arrived at in reference 
to the subject of inquiry. A communication from Prof. Cayley 
