782 
crustaceans, so interesting from the analogy to Trilobites, presented 
by allied genera, are rarely found in single specimens, but in groups, 
and therefore present this additional agreement with the habits of re- 
cent species. The fossils appear to have been deposited tranquilly 
at the bottom of the water which they inhabited, being always found 
imbedded with their legs downwards, and they are generally well pre- 
served. Thewhole of the freshwater remains of these Wealden beds, 
including the testacea, afford the natural characters of such deposits 
by yielding abundance of specimens, but few genera. 
Associated with the above-mentioned organic remains of the Vale 
of Wardour, Mr. Brodie has obtained three species of small fishes 
quite distinct, he says, from those found at Lady Down and Chicks- 
grove. With a single exception they were all procured at one spot. 
None of the localities mentioned in the paper afforded the least 
trace of the “ dirt-bed,’’ or of Cycadeoidea. 
4. “On the Geology of Egypt.’’ By Lieut. Newbold of the Ma- 
dras Army, F.R.S. Communicated by the President. 
Mr. Newbold first describes the physical features of Egypt, and 
2ndly, the formations of which the country is composed. 
I. Physical Features.—Atter alluding to the natural boundaries of 
Kgypt, namely, the Mediterranean on the north, the Libyan desert 
on the west, the mountains of Nubia on the south, and the Red Sea, 
with the Isthmus of Suez, on the east, and stating that the area thus 
circumscribed comprises about 100,000 square miles, the author shows 
that Egypt has three great physical divisions: 1. the mountainous 
region extending between the Red Sea and the Nile; 2. the deserts 
east and west of the Nile; and 3. the fertile valley of that river, with 
its delta. 
The mountainous region is naked and dreary in aspect, on account 
of the deficiency of springs, rain, and dew; and it presents bare or 
sand-covered rocks, intersected by deep ravines. The peculiarly ta- 
bular features of Central and part of Upper Ngypt are due to the ho- 
rizontal stratification of the prevailing limestone, which supports the 
desert districts, and terminates near the banks of the Nile, from Esneh 
to Cairo, in mural escarpments. Between Kossier and Ghennah the 
aspect is rendered more varied and irregular by pinnacles and dome- 
shaped masses of plutonic or hypogene rocks. The deserts present 
a series of undulating plains sometimes studded with clusters of low 
hills, and are covered chiefly with unproductive saline, often calca- 
reous and gypseous sand, marl, and gravel. The Oases of the deserts 
and the mountainous region, Mr. Newbold regards simply as valleys, 
supplied with moisture either by springs or by the drainage-water of 
the deserts, held up by the impervious clay constituting the subsoil. 
In a few cases the moisture, he thinks, may be due to percolation 
from the Nile. The greatest altitude of the desert between Suez and 
Cairo is about 700 feet above the ‘‘ ocean;”’ and its general charac- 
ter between the Red Sea and the Nile is that of a flattish irregular 
plateau rising towards the centre and terminating in each direction 
in abrupt escarpments. ‘The flat marshy districts between Suez and 
