Dec. 23, 1869] 
mergence of the district. He supposed them to have passed from 
Shap Fell by what isnow the pass of Stainmoor. Thus he ascribed 
the formation of the ‘‘ great chalky clay” to the extrusion from the 
sea-foot of a great sheet of ice, of materials abraded by the 
latter, the land being depressed 600 to 700 feet below its present 
level ; and that of the clay without chalk and with boulders of 
Shap Fell granite to deposition during a period of much greater 
depression (about 1,500 feet), throughout which the sea bore 
much floating ice. He considered that the ‘great chalky 
clay” indicated a long perod during which the land, with its 
enveloping ice, remained stationary, and that during this period, 
when intense cold prevailed, the arctic fauna of Bridlington 
became established. He thought that the recommencement of 
subsidence was indicated by the reddish-brown or brownish- 
purple sediments of Holderness, in which some chalk occurs. 
He then indicated the species of mollusca which have occurred 
in the purple clay without chalk about Scarbro’ and Whitby, all 
of which were said to belong to existing forms, and thus be in 
accordance with the date assigned by him to that deposit. The 
mollusean fauna of Moél Tryfane was referred to by the author, 
who stated that he regarded it as belonging to the period of 
emergence from the deepest depression during which the clay 
without chalk was assumed to have been deposited, 7.¢., to the 
earliest part of the post-glacial period, to which the stratified 
drifts of Scotland are referred by Mr. A. Geikie. Mr. Gwyn 
Jeffreys had found the shells of Kelsea and elsewhere in York- 
shire to be mainly arctic; and Mr. Prestwich, in his paper on 
the boulder-clay near Hull, had first pointed out their glacial 
character. In the late dredgings in H.M.S. /orcupine several 
of the species before known as fossil at Bridlington, but not as 
existing in the British seas, had been discovered. In fact, he 
believed that the Bridlington species, with but few exceptions, 
had now been found in the British seas. Similar species had 
also been found in the boulder-clay in Scotland. Prof. Ramsay 
was pleased to find the author’s views so closely correspond with 
his own published some years ago as to the glacial phenomena 
of North Wales, though based on another part of the country. 
He thought that shells might be found by careful search in the 
low-lying boulder-clay in other places than those enumerated, as 
they had been discovered in the western part of England. Mr. 
Prestwich, though inclined to accept the divisions of the boulder- 
clay in Yorkshire as suggested by the author, was not so clear 
as to his divisions in the south. He thought the presence of 
chalk in the clay might be traced to the contiguity of the outcrop 
of the chalk stratum. The shells being to a very great extent 
recent, the grouping might be due to accidental or local circum- 
stances. ‘Lhe Chillesford clays, in his opinion, mark the com- 
mencement of the great glacial period. Mr. Etheridge suggested 
that Mucula Cobboldia, Cardita similis, and some other shells 
not found in the British seas, proved the arctic character 
of the Bridlington fauna. Sir Charles Lyell remarked 
that if the fauna of the lower and middle glacial really corre- 
sponded so closely with that of the crag, it afforded a strong 
argument against their being of the same age as the Brid- 
lington beds. Perhaps, eventually, some paleontological con- 
nection might be traced throughout the series, and a chrono- 
logical scale established. The President suggested a difficulty 
in the marine transport of ice from Shap Fell to Bridlington, 
not only from the wind blowing rarely in the necessary direc- 
tion, but from the current caused by the great submerged ridge 
also tending to carry any bergs in another direction. He 
thought the transport by sheet-ice more probable. The Rev. 
J. L. Rome had traced the Shap granites over the valley of ° 
the Eden, across Stainmoor, to the Yorkshire side. There 
might have been difficulties in their transport, but there they 
are. Though they were found in Teesdale, yet the intervening 
ridge of millstone-grit, 2,000 feet, had prevented them finding 
their way into Swale Dale. Mr. Searles V. Wood, jun., stated 
that he had relied on Mr. Gwyn Jeffreys’s works for his classifi- 
cation of the shells as being arctic or otherwise. He regarded 
the succession of the various members of the glacial series as 
well established, and as borne out also by the molluscan re- 
mains. He utterly repudiated the notion that the Chillesford, 
Iridlington, and Kelsea Hill beds were on the same horizon. 
He believed the whole of the Scotch beds to be newer than 
those of England. He quoted Professor Phillips as suggesting a 
change in the elevation around Shap Fell since the dispersion of 
the boulders, and offered as his own explanation of the hypo- 
thesis, that the passes by which the boulders travelled were those 
which, though at the higher levels, were the soonest freed from 
NATURE 
223 
ice. He thought that the direction of the current was influ- 
enced by other causes than the general trend of the rocky divid- 
ing ridge. 
The following specimens were exhibited to the meeting ;— 
Fossiliferous Pebbles from Budleigh Salterton, exhibited by 
Professor Tennant and R. Etheridge, Esq. 
Zoological Society, December 9.—Dr. E. Hamilton, V.P., 
in the chair. The Secretary read a list of the more remarkable 
of the recent additions to the Society’s menagerie, amongst 
which were particularly noticed two gibbons (//y/obates lar), 
deposited by G. S. Roden, Esq. An extract was read from a 
letter addressed to the Secretary by Capt. G. E. Bulger, C.M.Z.S., 
correcting an error in a former paper by him on the birds observed 
at Wellington, in the Neilgherry Hills, published in the Society’s 
Proceedings. Professor W. H. Flower, F.R.S., gave some 
account of the external characters of the fin-whale, recently 
stranded in Langston Harbour, near Portsmouth, which he 
considered referable to the species usually called Balenaptera 
musculus. Mr. ¥lower concluded his remarks with a sketch of 
the species of the Balenoid, or whalebone-producing, whales, 
which occur in the British seas. These, according to our present 
knowledge of them, appear to be six in number, namely :— 
Balena biscayensts, Megaptera longimana, and Balenoptere 
musculus, Sibbaldi, laticeps, and rostrata. A communication was 
read from Surgeon Francis Day, F.Z.S., on the fresh-water fishes 
of Burmah, being an account of the specimens of this class of 
animals obtained during a recent inspection of the fisheries of 
Pegu, and during a short visit paid to the capital of Upper 
Burmah. A second communication was read from Surgeon 
Francis Day containing the third part of his critical notes on the 
fishes of the Calcutta Museum. Mr. G. French Angas gave 
descriptions of twelve new species of land-shells belonging to 
different subdivisions of the family /Ye/icide, from the Western 
Pacific Islands. Mr. P. L. Sclater read a list of the birds that 
had bred in the Gardens of the Society during the past twenty 
years. The total number of species enumerated in this list was 
108. Mr. R. B. Sharpe pointed out the characters of a new 
kingfisher belonging to the genus Zazzysiftera, which he proposed 
to call 7. £/votz, A communication was read from Mr. Harper 
Pease on the classification of the molluscs of the genus /fe/icter. 
A paper was read by Messrs. P. L. Sclater and O. Salvin on 
birds collected by Mr. W. H. Hudson at Conchitas, near Buenos 
Ayres, being their third communication to the Society upon this 
subject. Mr. Sclater exhibited and pointed out the characters of 
two new species of birds of the sub-family Sya//axine, proposed 
to be called Syzallaxts curtata and Leptasthenura andicola, A 
communication was read from Capt. G. E. Bulger, entitled Notes 
on Two Animals observed near Wind-Vogel-berg, South Africa. 
Mr. R. Swinhoe, F.Z.S., read a paper on the Cervine Animals 
of the Island of Hainan, Southern China, which he stated to be 
referable to three species, namely :—Cervulus vaginalis, Cervus 
(Panolia) Eldi, and a Rusine Deer allied to Cerwus hippelaphus. 
A communication was read from Mr. W. T. Blanford on the 
species of //yrax inhabiting Abyssinia and the neighbouring 
countries, which he believed to be four in number. Dr. J. E, 
Gray communicated the description of a new species of Zmys, 
living in the Society’s Gardens, which he proposed to call 
£. flavipes, from an unknown locality. 
Mathematical Society, December 9.—Professor Cayley, 
president, in the chair. Professor H. J. S. Smith communicated a 
note on the Focal Properties of two Correlative Figures. This paper 
was an appendix to a former paper by the same author, on the 
Focal Properties of Homographic Figures. By the term “focal 
properties”? are intended those properties which arise from 
considering the imaginary circular points at an infinite distance in 
either figure, and the points corresponding to them in the other 
figure. These properties appear to be much less varied in their 
character in the case of two correlative figures than in the case 
of two homographic figures ; and the two following theorems 
(of which the first is well known) will suffice to give an idea 
of the general nature of the results:—1. In two correlative 
figures in space there are always two corresponding tetra- 
hedra, such that three adjacent edges of each are rectangular ; 
the three edges opposite to these being at an infinite dis- 
tance, and the edges at a finite distance in either figure 
corresponding to the edges at an infinite distance in the 
other. 2. If we consider any point in either figure, and its corre- 
lative plane in the other, we have two definite planes passing 
through the point, and two corresponding points upon the plane, 
which may be called respectively the cyclic planes of the point 
