June 8, 1899] 
IN ZL TORE 
143 
resembles that of a monotreme mammal rather than that of any 
existing reptile. There appears to be a slender pre-pollex 
including three bones. The only other example of this structure 
in the Trias is in the Theriodont reptile 7ev¢odesmus, in which 
it is less definite. This character may add to the interest of 
other footprints from Stourton, which in the form of the foot 
approximate to Anomodont reptiles from the Karoo Beds of 
Cape Colony.—On, the distal end of a mammalian humerus 
from Tonbridge, by Prof. H. G. Seeley, F.R.S. The bone 
described in this communication was found in 1898 by Mr. 
Anderson on the bank of the river Medway, near Tonbridge. 
It was seen projecting from reconstructed rock which contained 
fragments of flints among other materials. Traces of matrix at 
the distal end show that the specimen has been derived from 
quartz-sand bound together with limonite, suchas might occur 
in the Hastings Sand, Wealden Clay, or Lower Greensand. 
Conditions of mineral structure and osteological character 
incline the author to believe that the bone was originally 
contained in the Wealden Clay. The fossil is 4 inches long, 
and indicates a humerus which may have been 6 inchesin length 
when perfect, as large as that of a wolf but smaller than that of 
a bloodhound. The form of the shaft precludes any comparison 
with the carnivora, and indicates a resemblance to ungulate 
types. When the bone is held vertically and seen from the 
front, the condyles are oblique—a character not observed in any 
other animal. The weight of evidence appears to incline 
towards reference of the fossil to the Artiodactyla, but it 
probably indicates a new family type. —On evidence of a bird 
from the Wealden Beds of Ansty Lane, near Cuckfield, by Prof. 
H. G. Seeley, F.R.S. A fragment of bone found, by Mr. 
Neville Jones, a member of the London Geological Field 
Class, embedded in sandstone was identified by the author as 
probably the distal end of the femur of a bird. The external 
condyle is not only larger and deeper than the inner, but is 
more prolonged distally—perhaps the most distinctive avian 
character of the bone. Colyméus is the only existing bird to 
which the fossil makes any approximation, but the resemblance 
is distant and not suggestive of near affinity, and it is interesting 
that the cretaceous birds show so marked an affinity with that 
type. The resemblances of the dinosaurian and crocodilian 
femora with this type are such that almost every individual 
feature of the bone can be paralleled in some fossil referable to 
these groups, but there are no British dinosaurs of so small a 
size or possessing some of the marked features shown by this 
bone.—Notes on the rhyolites of the Hauraki Goldfields (New 
Zealand), by James Park and Frank Rutley ; with analyses by 
Philip Holland. Part i. of this paper, by Mr. J. Park, gives a 
description of the rhyolites as seen in the field. After a rest 
from volcanic action during the secondary period, the tertiary 
eruptions burst forth and were more widespread than those of 
recent times. In the Hauraki Peninsula, the basement palzeozoic 
rocks are covered by richly fossiliferous marly clays and lime- 
stone of Lower Eocene age, and these bya vast accumulation of 
andesitic lavas and tuffs, in places 3000 feet thick. These 
andesites are the gold-bearing rocks of the district, and they are 
succeeded by rhyolitic lavas and ashes. Both andesites and 
rhyolites were influenced by solfataric action, resulting in 
siliceous deposits rich in gold and silver. The rhyolites rest on 
rocks probably of Upper Miocene age, and are followed by 
Pleistocene and recent deposits ; so that they probably range 
from older to newer Pliocene in date. Part ii. contains the 
observations of Mr. Rutley on the petrology of the rhyolites. 
The rocks present occasional occurrences of perlicity, and the 
lithoidal types sometimes owe their characters to subsequent 
devitrification, sometimes to the effect of cooling on, or 
immediately after, eruption. Reheating has at times reduced 
the felspars to the condition of felspar-glass. Although 
plagioclase-felspar is common, the analyses indicate that the 
series must be retained with the rhyolites, it being quite possible 
that some of these minerals may have been derived from the 
andesites. —On the progressive metamorphism of some Dalradian 
sediments in the region of Loch Awe, by J. B. Hill, R.N. 
(communicated by Sir A. Geikie, F.R.S.). The region under 
discussion contains two principal series of rocks, passing one 
into another without a break, and conveniently referred to 
the Dalradian System: (1) The Ardrishaig Series (phyllites 
and fine-grained quartzites). (2) The Loch Awe Series (black 
slates, limestones, grits, and quartzites). The latter series lies 
in a gentle trough of the former. Even in their most altered 
state, the clastic nature of the rocks of the Loch Awe Series is 
NO. 1545, VOL. 60] 
apparent. Both series are pierced by innumerable intrusive 
sills of epidiorite, hornblende-schist, and  chlorite-schist, 
modified diorites and gabbros, which effect contact-meta- 
morphism in the bordering sediments. Intrusive rocks of post- 
schistose date also occur, like the Glenfyn granite, the granite 
of Ben Cruachan, and smaller masses of granite, monzonite, 
hyperite, ultrabasic rocks, quartz-porphyries, felspar-porphyries, 
porphyrites, and lamprophyres ; these are in their turn cut by 
dolerite and basalt-dykes. All these rocks exhibit progressive 
metamorphism when traced towards the north-east and towards 
the Central Highlands, a character best seen in the loop formed 
by the rocks near the head of Loch Awe. Although the author 
does not go very fully into the question of the causes of the 
progressive metamorphism exhibited in tracing these rocks 
towards and into the Central Highland schists, he had reason 
to suspect that “‘ the intense regional type of metamorphism was 
linked with the same phenomena that afterwards resulted in the 
irruption of the granite-masses.”’ 
PaRIs. 
Academy of Sciences, May 29.—M. van Tieghem in the 
chair.—On isothermal surfaces, by M. Gaston Darboux.—On 
the laws of pressures in guns, by M. Vallier. A theoretical 
discussion of the distribution of pressure from point to point of 
the barrel during firing.—On cyclic pencils which contain a 
system of geodesics, by M. C. Guichard.—On the series of 
Dirichlet, by M. Lerch.—On the true polarisation of dielectrics 
placed within an electric field, by M. H. Pellat. The hypothesis 
is advanced that polarisation is not instantaneous ; but that a 
dielectric, solid or liquid, placed suddenly in an electric field, 
takes a polarisation which increases with the time, reaching a 
maximum asymptotically. If the field ceases, the polarisation 
decreases gradually, becoming zero at the end of a certain time, 
theoretically infinite. The results of an experimental study 
are in agreement with this hypothesis.—Polymerisation of 
abnormal vapours: nitrogen peroxide and acetic acid, by M. 
A. Leduc. In a previous paper, the author has shown that the 
variations in the density of chlorine with temperature are in 
perfect agreement with the theory of corresponding states, 
and the assumption that a dissociation of chlorine molecules 
has taken place is unnecessary. An application of the same 
method to the cases of nitrogen peroxide and acetic acid 
shows that the molecule is clearly dissociated. —On the 
measurements, in terms of a wave-length as unit, of a quartz 
cube, of 4 cm. length of side, by MM. Ch. Fabry, J. Macé de 
Lépinay, and A. Perot. The measurement was effected by 
means of the interferential method previously described, the 
variations between the individual readings being of the order 
of 1 in 1,000,000.—Bravais points and poles, by M. Pierre 
Lefebvre.—On the estimation of hydrogen phosphide in gaseous 
mixtures, by M. A. Joannis. A solution of copper sulphate 
cannot be employed to estimate hydrogen phosphide in gaseous 
mixtures, except in the absence of gases absorbable by copper 
salts. The copper sulphate solution must always be employed 
in considerable excess.—Separation and estimation of traces of 
chlorine in presence of a very large excess of bromide, by M. 
H. Baubigny. The method of copper sulphate and potassium 
permanganate is employed, and analyses of samples of potassium 
bromide sold as pure showed that a trace of chlorine was in- 
variably present, O*I per cent. of chlorine being the minimum, 
—Properties of some mixed haloid salts of lead, by M. V. 
Thomas.—On the quantitative separation of cerium, by MM. 
G. Wyrouboff and A. Verneuil. The method suggested is 
based upon the solution of the mixture of oxides in 
nitric acid, and subsequent polymerisation of the oxide 
in presence of sulphuric acid. The test analyses given 
are very satisfactory.—The enantiomorphic structure of 
Z- and y-benzylidene-camphors as revealed by corrosion figures, 
by M. Minguin.—Mixed combinations of phenylhydrazine 
and another organic base with certain metallic salts, by M. 
J. Moitessier.—Study of some oxymethylenic derivatives of 
cyanacetic ethers, by M. E. Grégoire de Bollemont.—Centro- 
some and fecundation, by M. Félix Le Dantec.—On the 
variations and specific grouping of the American Peripate, 
by M. E. L. Bouvier.—Spontaneous asphyxia and the pro- 
duction of alcohol in the deeper tissues of ligneous stems 
under natural conditions, by M. Henri Devaux. A study of the 
respiratory coefficients of the internal layers of certain plant 
stems showed that the ratio CO,/O, increases rapidly with the 
temperature. This increase of carbon dioxide, according to the 
