1891.] The Origin of the Galapagos Islands. 217 
ON THE ORIGIN OF THE GALAPAGOS ISLANDS. 
BY G. BAUR. 
An islands can be divided into two principal groups. 1. Is- 
lands developed from continents or larger bodies of land 
through isolation or subsidence : continental islands. 2. Islands 
not developed from continents, but from submarine portions of 
the earth : oceanic islands. The flora and fauna of the first group 
will be more or less Aarmonic,—that is to say, the islands will be 
like satellites of the continent from which they developed, and the 
whole group comparable to a planetary system. The flora and 
fauna of the second group will be disharmonic,—that is to say, it 
will be composed of a mixture of forms which have been intro- 
duced accidentally from other places. It is evident that the first 
group of islands will be affected in the same way ; there will be 
immigrants from other localities besides the original inhabitants. 
Continental islands, therefore, may be composed of two floral and 
faunal elements : first, an original (endogenous) one ; and second 
a secondary (exogenous) one. Oceanic islands, however, will only 
contain a secondary (or exogenous) floral and faunal element. 
We will now proceed to examine whether the Galapagos belong 
to the first or second group of islands ; whether they are detached 
portions of a continent, or of new origin emerged from the 
sea. These islands, better than any other group, afford a splen- 
did opportunity for the examination of this question. They had 
never been inhabited before their discovery by the Spaniards in - 
the sixteenth century. Buccaneers and whalers made the islands 
a place of frequent resort ; but it was not before 1832 that a small 
colony was established on Charles Island, which, however, was 
soon abandoned again. To-day a small settlement is found on’ 
Chatham Island only, under the management of Sefior Manuel 
Cobos. The only animals which seem to have been seriously 
affected by these intruders are the tortoises, which had once been 
so very numerous on all the islands. On some of them at least— 
Charles Island, for instance—they are extirpated; but it is 
