94 
burning of the grass in autumn, or by reason of some pecu- 
liarity in the climate, or exposure, is a question on which 
some difference of opinion has been expressed. A discussion 
followed, from which it appeared that the author of the paper 
had not definitely settled the problem.—The Rev. O. Pickard 
Cambridge, F.R.S., communicated a new list of British and 
Irish spiders. After reviewing the existing literature on the 
subject, and the materials which had come to hand since 1881 
for a new and revised list of species, the author pointed out that 
the present paper was not intended merely for the use of authors 
or collectors interested in local faunas, but to give (with refer- 
ences to primary authorities) the spiders at present known to belong 
to Great Britain and Ireland, leaving the question of their distri- 
bution, abundance, or scarcity to be dealt with at some future 
time, when the present scanty number of spider-collectors might 
have increased. At present, large areas of varied natural 
characters, in some cases whole counties, and many maritime 
districts, were entirely unexplored, so far as the Arachnology is 
concerned.—Prof. R. J. Anderson communicated a_ paper 
entitled ‘* Imitation as a source of anomalies.” Commenting 
upon the statement made by Profs. Krause and Testut that 
muscular anomalies are rare in the lower animals, whilst in man 
they are very common, the author considered it remarkable that 
no single instance had been authenticated in recent times of a 
mammal fairly attempting to utter a human voice-sound, 
although this did not apply to birds. He suggested that in the 
attempt to imitate, the mental act, or volition, if sustained, 
might favour a change of a moderate nature, and that such a 
change might be either progressive or retrogressive. 
Geological Society, April 26.—W. Whitaker, F.R.S., 
President, in the chair.— Prof. Emmanuel Kayser, of Marburg, 
was elected a Foreign Member; and Prof. Franz Loewinson- 
Lessing, of Dorpat, and Prof. R. Zeiller, of Paris, were elected 
Foreign Correspondents of the Society.—On limestone-knolls 
in the Craven district of Yorkshire and elsewhere, by J. E. 
Marr, F.R.S. The author begins with a general account of the 
district, partly founded on the published work of Mr. R. H. 
Tiddeman, but substantiated by his own observations. The 
Lower Carboniferous rocks north of the Craven Fault-system 
differ in character and thickness from those on the south ; they 
exhibit little disturbance on the north, but on the south they are 
thrown into a series of folds, while it is also on this side that the 
knobs of limestone called £70//-reefs by Mr. Tiddeman occur. 
The prominent features of the knolls are the crystalline 
character of the limestone, the horizontality of bedding in the 
interior of the knolls, the general parallelism of the bedding of 
the exterior to the contour of the knolls, and the obscurity of 
the bedding. Fossils, when present, are usually very perfectly 
preserved and undistorted ; breccias are frequently found in the 
shales bordering the knolls and, much less commonly, in the 
limestone of a knoll itself. Evidence of movement in the knolls 
is seen in the lenticular character of the beds of limestone, in 
visible folded structures, the termination of lenticular beds in 
hooks against a divisional plane, and in the shales by the 
presence of a structure undistinguishable from cleavage. 
Dolomitised and silicified limestones are frequently associated 
with the knolls, and the perfection of the quartz-crystals in 
certain examples of the latter variety of rock suggests crystallis- 
ation during relief of pressure. The breccias belong to three 
main types: (1) Fragments of limestone in a matrix of similar 
material ; (2) large nodules of black limestone enwrapped in 
shales; (3) various limestone-fragments in a fine calcareous 
paste. Examples of each type are described, and each is ex- 
plained as resulting from some form of earth-movement. 
Breccias of similar types are found to be produced out 
of grit-fragments, and in places the grits are found to be 
piled together by faulting so as to produce knolls, which some- 
what resemble those in the limestone. Dealing with the nature 
of the movements, the writer argues that the Middle Craven 
Fault is an overthrust from the north, and that the Limestone 
S ies has undergone differential movements with respect to the 
hard Lower Paleozoic rocks beneath and the massive Millstone 
Grit above. The limestones have been squeezed-out from under 
the synclines, and they have accumulated under the anticlines 
where the pressure was relieved. In conclusion, a number of 
examples of knolls are cited from other localities which show 
similar features, such as the limestones of Keisley, Millom, and 
near Dalton-in-Furness, some of the Devonian limestones near 
Torquay, the Lep/aena-limestone of Dalecarlia, and the Devonian 
imestone of Kofeprus in Bohemia. — The limestone-knolls 
NO. 1543. VOL. 60] 
INL AR Tele, 
(May 25, 1899 
below Thorpe Fell, between Skipton and Grassington in Craven, 
by J. R. Dakyns. A band of limestone runs from Cracoe 
towards the north-east, folded in an anticline and dipping under 
shales. In several places the top of the limestone is brecciated 
and the overlying (Bowland) shale contains fragments of lime- 
stone. The limestone forms five abrupt conspicuous hills. The 
rocks in most of these hills are not bedded, and where they are 
bedded the dip is confusing ; both in exposures outside of these 
and in adits inside, the limestone in some cases is amorphous 
and without any sign of bedding. The author considers the 
absence of bedding in the limestone to be a very important 
feature ; for in the country south of the North Craven Fault, though 
the rockis excessively contorted, its bedding has not been destroyed, 
—On three species of Lamellibranchs from the Carboniferous 
Rocks of Great Britain, by Dr. Wheelton Hind. The first part 
of this paper describes a new species of dAzthracomya which 
occurs in the North Staffordshire and Manchester coalfields at 
horizons higher than that characterised by 4. Phzl/épst. The 
fossilis found at Etruria, Bradwell, Stoke-on-Trent, and Fallow- 
field. It appears to indicate a special zone of shales and 
Spirorbzs-limestone about 300 feet below the Penkhull Sand- 
stone, and to be the only molluscan form known from the zone. 
A new species of Cardenzcola is next described, partly trom 
specimens previously supposed to be a gasteropod, a brachiopod, 
or even a crustacean, and partly from better-preserved specimens 
obtained from calcareous bands about ten yards above the Bassey 
Mine Ironstone in North Staffordshire. It appears to be the 
latest species of this genus known, and to occur in higher beds 
than any other species. Lastly, a new species of Ctenodonta 
from Penton Linns (Dumfriesshire) is described. It occurs in 
a marine shale below the highest limestone of the locality, in 
beds referred to the horizon of the Hurlet Limestone by the 
officers of the Geological Survey. The bed contains gastero- 
pods, crinoids, cephalopods, &c., with Productus giganteus. 
The species has some resemblance to C. Ha//:, Barrois, found 
in Spain. 
DUBLIN. 
Royal Dublin Society, March 22.—Prof. D. J. Cunning- 
ham, F.R.S., in the chair.—Dr. G, Johnstone Stoney, F.R.S., 
read a paper entitled ‘‘ Survey of that part of the range of 
nature’s operations which man is competent to study.’”—April 
19.—Prof. G. F. FitzGerald, F.R.S., in the chair.—Prof. Letts 
and Mr. R. F. Blake presented the second part of their paper 
on the carbonic anhydride of the atmosphere, dealing with the 
amount and causes of variation. The authors discuss (1) the 
chief natural causes of evolution, (2) those of absorption, and 
(3) the regulating agencies, and suggest that the chief per- 
manent natural source of evolution—namely, volcanic and 
subterranean emanations of carbonic anhydride—is kept in check 
by the absorption of the gas during rock disintegration, and 
eventually by cretaceous organisms which permanently remove 
(though of course indirectly) carbonic anhydride from the atmo- 
sphere, thus diminishing the supply of carbon necessary for the 
sphere of organic action. They also suggest that this ‘‘ de- 
gradation” of carbon may finally lead to the extinction of all life 
on the globe. In the seccnd section of the paper, the question 
of the temporary fluctuations in the amount of atmospheric 
carbonic anhydride is considered. These at the lowest 
estimate at times reach 10 per cent. of the total 
quantity. Each’ of the chief natural causes inducing 
chese variations, or supposed to induce them, is dis- 
cussed and the evidence reviewed; also the 7é/e which 
ground air plays in the phenomenon is considered. They pre- 
sent with the memoir a very carefully compiled list of the chief 
original papers which have appeared on the subject, as well as 
the abstracts of them.—Prof. G. F. FitzGerald communicated 
a paper, by Mr. D. H. Hall, on the concentration of soap solu- 
tion on the surface of the liquid. This paper records the results 
of experiments to determine whether there is any concentration 
of soap solution in the superficial film of the liquid. The re- 
sults showed that the soapy matter is so concentrated.—Dr. 
R. F. Scharff communicated a report on the Crustacea Schizo- 
poda of Ireland, by Messrs. Ernest W. L. Holt and W, I. 
Beaumont, in connection with the Royal Dublin Society’s 
Survey of Fishing Grounds on the West Coast of Ireland. 
The report includes a complete list of all Schizopods recorded 
from Irish localities. Two species, Parerythrops  obesa, 
G.O.S., and Afysidella typica, G.O.S., are added to the 
British list. A new genus, Dasymysis, is erected for the re- 
ception of A/ysis dongicornis, M.-Edw., Czerniaysky’s genus 
