400 
ISLAND LIFE. 
[part II. 
an active volcano 8,500 feet high ; and, as already stated, they 
are situated on a submarine bank with less than 500 fathoms 
soundings, connecting Madagascar with Africa. There is reason 
to believe, however, that these islands are of comparatively 
recent origin, and that the bank has been formed by matter 
ejected by the volcanoes or by upheaval. Any how there is 
no indication whatever of there having been here a land-con- 
nection between Madagascar and Africa ; while the islands 
themselves have been mainly colonised from Madagascar, to 
the 100-fathom bank surrounding which some of them make 
a near approach. 
The Comoros contain two land mammals, a lemur and a civet, 
both of Madagascar genera and the latter an identical species, 
and there is also a peculiar species of fruit-bat (. Pteropus 
comorensis), a group which ranges from Australia to Asia and 
Madagascar, but is unknown in Africa. Of land-birds forty-one 
species are known, of which sixteen are peculiar to the islands, 
twenty-one are found also in Madagascar, and three found in 
Africa and not in Madagascar; while of the peculiar species, 
six belong to Madagascar or Mascarene genera. 
These facts point to the conclusion that the Comoro Islands 
have been formerly more nearly connected with Madagascar 
than they are now, probably by means of intervening islets 
and the former extension of the latter island to the westward, 
as indicated by the extensive shallow bank at its northern 
extremity, so as to allow of the easy passage of birds, and 
the occasional transmission of small mammalia by means of 
floating trees. 1 
The Seychelles Archipelago . — This interesting group consists 
of about thirty small islands situated 700 miles N.N.E. of 
Madagascar, or almost exactly in the line formed by continuing 
the central ridge of that great island. The Seychelles stand 
upon a rather extensive shallow bank, the 100-fathom line 
around them enclosing an area nearly 200 miles long by 100 
miles wide, while the 500-fathom line shows an extension of 
nearly 100 miles in a southern direction. All the larger islands 
1 For the birds of the Comoro Islands see Proc. Zool. Soc. } 1877, p. 295, 
and 1879, p. 673. 
