Geological Society of London. V0 
or the sea. The author considered the effect of these sources of 
supply, and showed that, although the first three are doubtless to a 
certain extent correct, they are inadequate to account for some very 
important phenomena. The tidal silt, on microsecpic examination, 
is found to consist of both inorganic and organic materials, the former 
being argillaceous granules, grains of quartz, flint, etc.; the latter 
coccoliths, coccospheres, Foraminifera, occasional sclerites of Aleyonaria, 
fragments of Echinodermata, and triradiate spicules of Calcispongia, 
together with numerous spicules of siliceous sponges, a few Radiolaria, 
and a variable quantity of Diatoms. These organisms (described in 
detail by the author) are marine, and yet they occur on the banks 
of rivers at a great distance from a truly marine area. ‘lhe author 
showed it to be improbable that they can have been derived, at any 
rate to a considerable extent, either from the older formations through 
which the Severn flows, or from the alluvial flats of its estuary ; for 
although the latter do contain marine organisms of a generally like 
kind, the spicules, etc., indicate corrosion, and are generally not so 
well preserved as those which occur in the tidal silt. It seems, there- 
fore, necessary to conclude that a considerable portion of the organisms 
now present in this have been brought from the sea; but sponges are 
not known to grow in any quantity nearer Bristol than the coasts of 
Devon and Pembrokeshire. It would therefore appear that these 
organisms, contrary to what might have been expected, have been 
drifted up into the tidal estuaries of the river for a very considerable 
distance: The author concluded by describing in detail the alluvial 
tracts of the Severn, which he considers to have been formed (with 
certain differences of level) much as tidal deposits are formed at the 
present day; and by pointing out the bearing of his investigations on 
the question of the probable results of the discharge of sewage into 
tidal rivers. 
2. ‘Notes on a Collection of Fossils and Rock-specimens from 
West Australia, north of the Gascoyne River.” By W. H. Hudleston, 
Esq., M.A., F.G.S. 
This collection was forwarded to England by Mr. Forrest, who has 
been engaged for some time past in surveying the northern portion 
of the colony, and was accompanied by a map indicating the position 
whence the specimens were obtained. The author drew attention to 
a paper by Mr. Gregory, which appeared in the Quarterly Journal, 
many years ago, giving a brief description of the country as far as the 
Gascoyne river in lat. 25° S., together with some diagrammatic sections, 
which show a belt of sedimentary rocks between the sea and the 
crystalline plateau forming the interior of the country. This belt of 
sedimentary rocks widens materially towards the north, being about 
90 miles across on the parallel of the Gascoyne river. Amongst the 
rock-specimens in the Forrest collection are crystalline schists, etc., in 
which white mica and quartz are the most prominent minerals; and 
it is evidently from the degradation of masses of this class that the 
arenaceous rocks containing the fossils were derived; no limestone has 
been sent, but where the grits are largely charged with fragments of 
Encrinites, Polyzoa, etc., there is a proportionate increase of calcareous 
matter. No specimens of coal or of recognizable plants were forwarded. 
