154 REPORT—1843. 
considerably. The first generates great muddy tracts, which present a fauna 
peculiar to themselves: the second, though of short duration, deposits de- 
tached patches of conglomerate, and by the sudden settling of the fluviatile mud 
forms thin strata at the bottom of the sea, often containing the remains of ter- 
restrial and fluviatile animals, soon to be covered over by marine deposits with 
very different contents. From the influx of a great river we may have tropical 
or subtropical, terrestrial or fluviatile forms mingled with temperate marine. 
Thus among forty-six species of Testacea collected by Captain Graves and Mr. 
Hoskyn on the shore at Alexandria, there are four Egyptian land and fresh- 
water Mollusca, three of which are of truly subtropical forms, viz. Ampullaria 
ovata, Paludina unicolor, and Cyrena orientalis. The marine associates of 
these are, however, noways more southern in appearance, and for the most 
part identical as species with the Testacea which strew the shore at Smyrna 
or at Toulon, in the former case mingled with Melanopsis, in the latter with 
characteristic European Pulmonifera. 
When the sea washes the shores of Egypt, remains of vegetables of a sub- 
tropical character become mingled with similar associations of marine Mol- 
lusca with those in which the relics of more northern plants become im- 
bedded in the waters of the Black Sea. The Nile may carry down the woods 
and animals of Upper Egypt, the Danube those of the Austrian Alps. De- 
posits presenting throughout similar organic contents of marine origin, may 
contain at one point the relics of marmots and mountain salamanders, at 
another those of ichneumons and crocodiles. 
Vegetable remains are being imbedded in strata forming at very different 
depths. Thus olive leaves were scattered among the mud dredged from a 
depth of 30 fathoms on the coast of Lycia, at Symboli, and date stones and 
monocotyledonous wood from a depth of nine fathoms off Alexandria. Of 
course the associated Mollusca were very distinct in each instance, in the 
first being members of the fourth, in the second of the second region of 
depth. 
Provinces of Depth. 
There are eight well-marked regions of depth in the eastern Mediterranean, 
each characterised by its peculiar fauna, and when there are plants, by its 
flora. These regions are distinguished from each other by the associations 
of the species they severally include. Certain species in each are found in 
no other, several are found in one region which do not range into the next 
above, whilst they extend to that below, or vice versd. Certain species have 
their maximum of development in each zone, being most prolific in indivi- 
duals in that zone in which is their maximum, and of which they may be re- 
garded as especially characteristic. Mingled with the true natives of every 
zone are stragglers, owing their presence to the action of the secondary in- 
fluences which modify distribution. Every zone has also a more or less ge- 
neral mineral character, the sea-bottom not being equally variable in each, 
and becoming more and more uniform as we descend. The deeper zones are 
greatest in extent ; so that whilst the first or most superficial is but 12, the 
eighth, or lowest, is above 700 feet in perpendicular range. Each zone is 
capable of subdivision in smaller belts, but these are distinguished for the 
most part by negative characters derived from the cessation of species, the 
range of which is completed, and from local changes in the nature of the sea- 
bottom. 
First Recion, or LirTorAL Zone. 
The first of the provinces in depth is the least extensive, and two fathoms 
