31 
longirostris, Mr. Sharpe considers identical with a species common 
in the tertiary deposits of the south of Spain. Small quantities of 
quicksilver have been found in several places in a bed of sand im- 
mediately above the blue clay or central division of the formation. 
(c.) Lower Tertiary Conglomerate-—This deposit consists in the 
upper part of distinctly stratified conglomerates, composed of lime- 
stone pebbles imbedded in a calcareous matrix; and in the lower 
of sands, grits, gravel, and marl. Within the district examined by 
Mr. Sharpe, it occurs only on the Lisbon side of the Tagus, forming 
a band from that city by Odivellas, Camarate, Loures, and Tojal, 
to the neighbourhood of Alhandra, on the banks of the Tagus, and 
skirting the western and north-western boundary of the Almada 
beds. ‘The conglomerate occurs also on some of the detached hills 
between Belem and the Bay of Cascaes. ‘The deposit dips to the 
south-east under the Almada beds at an angle of 10° or 15°, but in 
the lowest strata the dip is 30°. For a short distance south of 
Alhandra, the conglomerate rests upon the red sandstone, but 
throughout the remainder of its range upon basalt. No organic 
remains were noticed in the deposit. 
SECONDARY FORMATIONS. 
In few countries can the separation between the tertiary and 
secondary formations be more strongly marked than in the neigh- 
bourhood of Lisbon. ‘The deposits of the older class of rocks, Mr. 
Sharpe states, were disturbed and denuded previously to the com- 
mencement of the tertiary epoch, and an immense mass of basalt is 
interposed between the newest of the secondary rocks and the most 
ancient of the tertiary series. 
(d.) Hippurite Limestone.—The upper part of this formation con- 
sists of alternations of marl and limestone, succeeded by beds of 
limestone containing thin horizontal beds of flint; and the lowest 
part of various strata of compact limestone ; amounting in the whole 
to a thickness of above 500 feet. ‘The formation is confined to the 
north of the Tagus, where it presents several distinct bands, which 
rest upon the red sandstone, and are overlaid by basalt. ‘The most 
southern tract extends from Cascaes Bay nearly to Loures; another 
irregular strip ranges from Montelavar to a little to the eastward of 
Bucellas; and a third district, commencing near Villa Franca, 
stretches to the north beyond the range of Mr. Sharpe’s district. A 
portion of Lisbon also stands upon Hippurite limestone. In some 
parts, especially on the coast, the dip is slightly towards the 
south-east, but from Loures to beyond Bellas it varies from 30° 
to 50° in the same direction. The strata do not always rest con- 
formably on those of the subsequent red sandstone, for near Cas- 
caes, the limestone beds are horizontal, and the sandstone on which 
they lie is inclined at a considerable angle. ‘The narrow valley of 
Alcantara, close to Lisbon, is the line of a considerable fault, the 
strata dipping in opposite directions from the valley, or 15° towards 
the west, and 10° towards the east. Another anteclinal line inter- 
