March 2, 1871} 
NATURE 
357 
ees 
to the collection of the Indian Museum, Calcutta.—A second 
communication from Dr, Anderson contained the descriptions of 
eight new species of birds, recently collected by him during the 
Yunan expedition.—A_ paper was read by Mr. W. C. Atkinson, 
containing descriptions of some new species of Diurnal Lepi- 
doptera, discovered in Yunan by Dr. Anderson during the same 
expedition.—The Secretary communicated a paper by Mr. 
Edward Bartlett, containing observations on the habits and 
distribution of the monkeys of Eastern Peru, as observed during 
a recent four years’ sojourn on the Upper Amazons. 
Geological Society, February $.—Mr. Joseph Prestwich, 
F.R.S., president, in the chair. 1. ‘‘Onthe Punfield Formation,” 
by Mr. John W. Judd. Those formations, which have been de- 
posited under /luvio-marine conditions, and which yield at the 
same time marine, fresh-water, and terrestrial fossils, are of 
especial interest to the geologist, as they furnish him with a 
means of correlating the great fresh-water systems of strata with 
those of marine origin. At the bottom of the Wealden we have 
one such fluvio-marine series, the well-known Purbeck formation ; 
atits summit isanother, less known, but notlessimportant, for which 
the name of ‘‘ Punfield Formation ” is now suggested. Some of the 
fossils of the latter were first brought under the notice of geologists 
by Mr. Godwin-Austen in 1850, and their peculiarities have since 
been thesubject of remark by Prof. E. Forbes, Sir C. Lyelland others. 
The typical section of the beds is at Punfield Cove, in the Isle of 
Purbeck, where they are about 160 feet thick, and include several 
bands with marine shells. The lowest and most remarkable of 
these yields about forty well-defined species, many of which, as 
well as one of the genera, are quite new to this country. A sec- 
tion somewhat similar to that of Punfield is seen at Worborrow 
Bay. Inthe Isle of Wight, at Compton, Brixton, and Sand- 
down Bays, similar fluvio-marine beds are found at the top of 
the Wealden, and attain to a thickness of 230 feet. The marine 
bands here, however, yield but a very scanty fauna. Indications 
of the existence of beds of the same character and in a similar 
position are found in the district of the Weald. While the Pur- 
beck formation exhibits the gradual passage of the marine Port- 
landian into the freshwater Wealden, the Punfield formation 
shows the transition of the latter into the marine Upper Neo- 
comian (Lower Greensand). Thus we are led to conclude 
that the epoch of the English Wealden commenced before 
the close of the Jurassic period, lasted through the whole of 
the Tithonian and of the Lower and Middle Neocomian, and only 
came to a close at the commencement of the Upper Neocomian. 
In tracing the Cretaceous strata proper from east to west, they 
are found to undergo great modification, while the Neocomian and 
Wealden, which they overlap through unconformity, besides 
being greatly changed in character, thin out very rapidly. On 
stratigraphical and paleontological evidence, the Punfield for- 
mation is clearly referable to the upper part of the Middle Neo- 
comian. Its fauna has remarkably close analogies with that of 
the great coal-bearing formation of eastern Spain, which is of 
vast thickness and great economic value. The claim of the 
Punfield beds, equally with the similarly situated Purbeck series, 
to rank as a distinct formation, is founded on the distinctness of 
their mineralogical characters, their great thickness, the fact of 
their yielding a considerable and very well characterised fauna, 
and of their being the equivalent of a highly important foreign 
series. The president remarked that the limited amount of 
fresh-water formations in this country was an obstacle to their 
correlation, and stated that Constant Prevost had endeavoured to 
correlate the secondary fresh-water and marine formations. Mr. 
Godwin-Austen remarked upon the thinning out of the Lower 
Greensand, especially in France; upon the imperfection of 
our knowledge of the great Cretaceous formation, and upon 
the probability of the intercalation of fresh-water condi- 
tions in the Lower Greensand. The formation at Punfield 
seemed to present an intercalation of marine between purely 
fresh-water conditions. He indicated how a slight change 
of level might have intercalated marine conditions in the 
Wealden. The deposition of the White Chalk and Oolite 
occupied enormous periods (in both cases purely marine), 
during which the northern hemisphere was a great northern 
ocean ; and as the distribution of land and water was due to the 
operation of great cosmical laws, the duration of terrestrial and of 
the intermediate freshwater conditions was probably of equal length. 
Mr. Judd, in reply, said that he did not propose the term Pun- 
field formation as a definitive term, but only asa matter of conve- 
nience. He believed that strata could be positively identified by 
he organic remains contained in them, although the method may 

have been grossly abused. Physical investigations alone led to 
nothing but confusion, as might be seen by the stratigraphical 
attempts of the predecessors of William Smith. The name 
Vicarya for the shell which had been referred to was only provi- 
sionally adopted, on the authority of De Verneuil and other 
writers. 2. “Some remarks on the Denudation of the Oolites 
of the Bath district, with a theory on the Denudation of Oolites 
generally.” By Mr. W. S. Mitchell. The author briefly 
referred to the theory according to which oolitic deposits were 
supposed to have been originally spread out in continuous sheets 
over the country which they occupy, and to owe their division 
into separate hills to the action of denudation after their original 
deposition and consolidation. He suggested, as an equally pro- 
bable hypothesis, that whilst the marls and clays of oolitic 
areas were probably originally deposited in continuous beds, the 
limestones in many cases may never have extended beyond the 
areas now occupied by them. He described the beds of lime- 
stone in the oolitic hills as thinning out towards the valleys on 
all sides, maintained that the limestones owed their origin to 
coral reefs, and cited several descriptions of coral islands by 
Prof. Jukes, to show the agreement in their structure with that 
which he ascribed to the oolitic hills. He assumed that in the 
event of a coral-area becoming one of sedimentary deposition, 
the sedimentary deposit would preserve intact the contour 
of the coral islands, and inferred that this has been the 
case in the Bath district, so that the Great Oolite 
cappings of the hills of that area may represent the ori- 
ginal contours of coral islands, exposed by the denudation of the 
Bradford clay. The amount of denudation undergone by the 
Great Oolite limestone he considered to be very small. The 
Inferior Oolite, on the contrary, he believed to have suffered 
denudation, and he considered that the course of the valleys 
formed by this agent was dependent on the form of the lime- 
stones capping the hills. Prof. Morris did not consider 
that the author’s views as to the oolitic masses round Bath 
being originally isolated coral banks with clay beds, although 
suggestive, were quite satisfactory. He pointed out that the 
strata on each side the valleys were similar in structure, mineral 
character, and fossil contents, and were once continuous ; and 
the present intervening deep valleys were rather due to the move- 
ments which the area had undergone in producing lines of weak 
resistance, subsequently assisted by the erosive action of perco- 
lating and running water, both in excavating and undermining 
the harder rocks, so as to cause them to bend towards the 
hill-sides, or fall in larger or smaller masses on their slopes. 
Mr. Mitchell, in reply, stated that he had seen both sides of 
what he regarded as coral reefs. He remarked that his hypo- 
thesis was arrived at by deduction, by inferring from observations 
on existing coral-reefs that those of the Oolites must have been 
covered up as islands. He remarked that if the oolitic beds had 
slipped, as described, upon the underlying clays, they could 
hardly range on opposite sides of the valleys. He noticed that 
the action of water in covering the blocks of Oolite with crys- 
tallised carbonate of lime would be protective, and remarked 
that the surface of the reefs was virtually a sea-bottom on which 
mollusca lived, so that their occurrence at corresponding levels 
in different hills was not to be wondered at. 
February 17.—Mr. Joseph Prestwich, F.R.S., president, 
in the chair.—The Secretary read the reports of the Council, 
of the Library and Museum Committee, and of the auditors. 
The general position of the Society, as shown by the state 
of its finances and the continued increase in the number 
of Fellows, was said to be very satisfactory. In present- 
ing the Wollaston Gold Medal to Prof. Ramsay, F.R.S., 
F.G.S., the President spoke as follows -—‘‘Prof. Ramsay,—I 
have great pleasure in presenting you with the Wollaston Medal, 
which has this year been awarded to you by the Council of the 
Society, in recognition of your many researches in practical and 
in theoretical geology. Distinguished as your services have been 
in connection with the Geological Survey since you entered upon 
it as the Assistant Geologist of Sir Henry De la Beche in 1841, 
and more particularly since your appointment as Local Director 
in 1845, during which period you have superintended and carried 
out the admirably minute style of mapping now general on the 
survey, and done so much in training its members in the field, 
you have not less distinguished yourself by your investigations of 
the higher problems involved in the study of geology. Your 
first work was on the Isle of Arran; and although then only a 
beginner, you, instead of taking the rocks to be what they 
looked, worked out what they were, and gave a new and inde- 
