cHaP. x.] THE PALZZARCTIC REGION. 201 
In addition to the territories now indicated as forming part 
of the Mediterranean sub-region, we must add the group of 
Canary Islands off the west coast of Africa which seem to be 
an extension of the Atlas mountains, and the oceanic groups of 
Madeira and the Azores; the latter about 1,000 miles from the 
continent of Europe, yet still unmistakably allied to it both in 
their vegetable and animal productions. The peculiarities of the 
faunas of these islands will be subsequently referred to. 
It seems at first sight very extraordinary, that so large and 
wide a sea as the Mediterranean should not separate distinct 
faunas, and this is the more remarkable when we find how very 
deep the Mediterranean is, and therefore how ancient we may 
well suppose it to be. Its eastern portion reaches a depth of 
2,100 fathoms or 12,600 feet, while its western basin is about 
1,600 fathoms or 9,600 feet in greatest depth, and a considerable 
area of both basins is more than 1,000 fathoms deep. But a 
further examination shows, that a comparatively shallow sea or 
submerged bank incloses Malta and Sicily, and that on the 
opposite coast a similar bank stretches out from the coast of 
Tripoli leaving a rarrow channel the greatest depth of which is 
240 fathoms. Here therefore is a broad plateau, which an 
elevation of about 1,500 feet would convert into a wide extent 
of land connecting Italy with Africa; while the same elevation 
would also connect Morocco with Spain, leaving two extensive 
lakes to represent what is now the Mediterranean Sea, and afford- 
ing free communication for land animals between Europe and 
North Africa. That such a state of things existed at a com- 
paratively recent period, is almost certain; not only because a 
considerable number of identical species of mammalia inhabit the 
opposite shores of the Mediterranean, but also because numerous 
remains of three species of elephants have been found in caves 
in Malta,—now a small rocky island in which it would be im- 
possible for such animals to live even if they could reach it. 
Remains of hippopotami are also found at Gibraltar, and many 
other animals of African types in Greece ; all indicating means 
of communication between South Europe and North Africa which 
no longer exist. (See Chapter VI. pp. 113—115.) 
Vou. L—15 
